diff --git a/src/api/studentTrainingAnswer.js b/src/api/studentTrainingAnswer.js
index 17c12a4..161310f 100644
--- a/src/api/studentTrainingAnswer.js
+++ b/src/api/studentTrainingAnswer.js
@@ -275,3 +275,13 @@ export function checkProductDevelopmentFactorsStepThree(payload) {
   }
   return request({ url: "/api/student-training-answers/product-development-factors/step-3/validate", method: "post", data: payload, headers: { repeatSubmit: false } });
 }
+
+export function checkProductDevelopmentFactorsStepFour(payload) {
+  const value = payload || {};
+  if (isStudentDemo()) {
+    if (!String(value.successFactors || "").trim()) return Promise.reject(new Error("请填写产品成功的关键因素"));
+    if (!String(value.failedFactors || "").trim()) return Promise.reject(new Error("请填写产品失败的关键因素"));
+    return Promise.resolve({ code: 200, data: { valid: true, message: "校验通过" } });
+  }
+  return request({ url: "/api/student-training-answers/product-development-factors/step-4/validate", method: "post", data: payload, headers: { repeatSubmit: false } });
+}
diff --git a/src/views/foundation/product-development-factors.vue b/src/views/foundation/product-development-factors.vue
index 66d37ec..a5f258f 100644
--- a/src/views/foundation/product-development-factors.vue
+++ b/src/views/foundation/product-development-factors.vue
@@ -112,6 +112,12 @@
             <div class="task-actions"><button type="button" class="btn-nav btn-submit" :disabled="saving" @click="saveAndGoToStepFour">保存并进入第 4 步</button><button type="button" class="btn-nav" :disabled="saving" @click="resetTraining"><el-icon><RefreshLeft /></el-icon>清空填写</button></div>
           </template>
 
+          <template v-else-if="currentStep === 3">
+            <p class="factor-intro">结合案例信息及前述步骤，分析案例资料中产品一成功的关键因素是什么，产品二失败的关键因素是什么。</p>
+            <label class="factor-intro">产品成功的关键因素：</label><textarea v-model="stepFourForm.successFactors" class="table-textarea summary-textarea" />
+            <label class="factor-intro">产品失败的关键因素：</label><textarea v-model="stepFourForm.failedFactors" class="table-textarea summary-textarea" />
+            <div class="task-actions"><button type="button" class="btn-nav btn-submit" :disabled="saving" @click="submitTraining">提交任务</button><button type="button" class="btn-nav" :disabled="saving" @click="resetTraining">清空填写</button></div>
+          </template>
           <div v-else class="step-placeholder">
             <p>第 {{ currentStep + 1 }} 步内容待配置</p>
             <span>已保存的分析可从上方步骤栏返回查看。</span>
@@ -133,7 +139,7 @@
 <script setup>
 import { Download, Operation, RefreshLeft } from "@element-plus/icons-vue";
 import { getTrainingTaskByKey } from "@/api/trainingTask";
-import { checkProductDevelopmentFactorsStepOne, checkProductDevelopmentFactorsStepTwo, checkProductDevelopmentFactorsStepThree, getStudentTrainingAnswer, saveStudentTrainingAnswer } from "@/api/studentTrainingAnswer";
+import { checkProductDevelopmentFactorsStepOne, checkProductDevelopmentFactorsStepTwo, checkProductDevelopmentFactorsStepThree, checkProductDevelopmentFactorsStepFour, getStudentTrainingAnswer, saveStudentTrainingAnswer } from "@/api/studentTrainingAnswer";
 import useUserStore from "@/store/modules/user";
 import TrainingAiSidebar from "@/views/components/TrainingAiSidebar.vue";
 import TrainingMaterialButton from "@/views/components/TrainingMaterialButton.vue";
@@ -206,6 +212,7 @@ const createStepThreeRows = () => STEP_THREE_FACTOR_ROWS.map((row) => ({ ...row,
 const stepOneRows = ref(createStepOneRows());
 const stepTwoRows = ref(createStepTwoRows());
 const stepThreeRows = ref(createStepThreeRows());
+const stepFourForm = ref({ successFactors: "", failedFactors: "" });
 
 const progressItems = [
   { text: "进行中：成功/失败产品对比", status: "doing" },
@@ -246,6 +253,7 @@ async function loadSavedAnswer() {
     }
     if (answer?.step2Answer) stepTwoRows.value = restoreRows(answer.step2Answer, createStepTwoRows);
     if (answer?.step3Answer) stepThreeRows.value = restoreRows(answer.step3Answer, createStepThreeRows);
+    if (answer?.step4Answer) stepFourForm.value = { ...stepFourForm.value, ...parseSavedAnswer(answer.step4Answer) };
     restoreCurrentStep(answer?.currentStep);
   } catch (error) {
     // Keep local draft when the backend answer cannot be loaded.
@@ -327,6 +335,7 @@ function loadDraft() {
       else stepOneRows.value = restoreRows(raw, createStepOneRows);
       if (draft?.stepTwo) stepTwoRows.value = restoreRows(draft.stepTwo, createStepTwoRows);
       if (draft?.stepThree) stepThreeRows.value = restoreRows(draft.stepThree, createStepThreeRows);
+      if (draft?.stepFour) stepFourForm.value = { ...stepFourForm.value, ...draft.stepFour };
     }
   } catch (error) {
     clearDraft();
@@ -354,7 +363,8 @@ function buildStepOneOutcome() {
 }
 function buildStepTwoOutcome() { return { title: taskTitle.value, factors: stepTwoRows.value.map((row) => ({ dimension: row.dimension, criteria: row.criteria, successAnalysis: row.successAnalysis, failedAnalysis: row.failedAnalysis })) }; }
 function buildStepThreeOutcome() { return { title: taskTitle.value, factors: stepThreeRows.value.map((row) => ({ dimension: row.dimension, criteria: row.criteria, successAnalysis: row.successAnalysis, failedAnalysis: row.failedAnalysis })) }; }
-function buildDraft() { return { stepOne: buildStepOneOutcome(), stepTwo: buildStepTwoOutcome(), stepThree: buildStepThreeOutcome(), currentStep: currentStep.value + 1 }; }
+function buildStepFourOutcome() { return { successFactors: stepFourForm.value.successFactors, failedFactors: stepFourForm.value.failedFactors }; }
+function buildDraft() { return { stepOne: buildStepOneOutcome(), stepTwo: buildStepTwoOutcome(), stepThree: buildStepThreeOutcome(), stepFour: buildStepFourOutcome(), currentStep: currentStep.value + 1 }; }
 
 function buildStepOneValidationPayload() {
   return {
@@ -378,6 +388,8 @@ function buildStepTwoValidationPayload() { return { factors: stepTwoRows.value.m
 function buildStepTwoAnswerPayload(saveAction = "SAVE", persistedStep = currentStep.value + 1) { return { step2Answer: JSON.stringify(buildStepTwoOutcome()), currentStep: persistedStep, submitted: false, saveAction }; }
 function buildStepThreeValidationPayload() { return { factors: stepThreeRows.value.map(({ dimension, successAnalysis, failedAnalysis }) => ({ dimension, successAnalysis, failedAnalysis })) }; }
 function buildStepThreeAnswerPayload(saveAction = "SAVE", persistedStep = currentStep.value + 1) { return { step3Answer: JSON.stringify(buildStepThreeOutcome()), currentStep: persistedStep, submitted: false, saveAction }; }
+function buildStepFourValidationPayload() { return buildStepFourOutcome(); }
+function buildStepFourAnswerPayload(saveAction = "SUBMIT", persistedStep = 4) { return { step4Answer: JSON.stringify(buildStepFourOutcome()), currentStep: persistedStep, submitted: true, saveAction }; }
 
 async function saveAndGoToStepTwo() {
   if (saving.value) return;
@@ -424,11 +436,13 @@ async function saveAndGoToStepFour() {
     proxy?.$modal?.msgSuccess("已保存，已进入第 4 步");
   } catch (error) { proxy?.$modal?.msgError?.(error?.message || "请完成供应链与成本控制、商业模式和市场反馈分析"); } finally { saving.value = false; }
 }
+async function submitTraining() { if (saving.value) return; saving.value = true; try { await checkProductDevelopmentFactorsStepFour(buildStepFourValidationPayload()); await saveStudentTrainingAnswer(TASK_KEY, buildStepFourAnswerPayload("SUBMIT", 4)); clearDraft(); proxy?.$modal?.msgSuccess("任务提交成功"); } catch (error) { proxy?.$modal?.msgError?.(error?.message || "请完成关键因素分析"); } finally { saving.value = false; } }
 
 async function resetTraining() {
   stepOneRows.value = createStepOneRows();
   stepTwoRows.value = createStepTwoRows();
   stepThreeRows.value = createStepThreeRows();
+  stepFourForm.value = { successFactors: "", failedFactors: "" };
   currentStep.value = 0;
   clearDraft();
   try {
diff --git a/tests/product-development-factors-step-one.static.test.cjs b/tests/product-development-factors-step-one.static.test.cjs
index 8246fac..9c3e9b3 100644
--- a/tests/product-development-factors-step-one.static.test.cjs
+++ b/tests/product-development-factors-step-one.static.test.cjs
@@ -40,5 +40,12 @@ assert.match(page, /buildStepThreeAnswerPayload\("SAVE", 4\)/, "step three must
 assert.doesNotMatch(page, /buildStepThreeAnswerPayload\("SUBMIT"/, "step three must not submit the task");
 assert.match(api, /export function checkProductDevelopmentFactorsStepThree\(/, "the student API must expose the step-three validator");
 assert.match(api, /product-development-factors\/step-3\/validate/, "the student API must call the step-three validation route");
+assert.match(page, /v-else-if="currentStep === 3"/, "the fourth form must render only on step four");
+assert.match(page, /产品成功的关键因素/, "step four must include success factors");
+assert.match(page, /产品失败的关键因素/, "step four must include failure factors");
+assert.match(page, /step4Answer/, "step four must save its own answer field");
+assert.match(page, /await checkProductDevelopmentFactorsStepFour\(buildStepFourValidationPayload\(\)\)/, "step four must validate before submit");
+assert.match(page, /buildStepFourAnswerPayload\("SUBMIT", 4\)/, "step four must submit the task");
+assert.match(api, /product-development-factors\/step-4\/validate/, "the student API must call the step-four validation route");
 
 console.log("product development factors step-one contract passed");