diff --git a/dto/gemini.go b/dto/gemini.go
index 489ebea534b4..f5a97dcbbdb5 100644
--- a/dto/gemini.go
+++ b/dto/gemini.go
@@ -160,7 +160,7 @@ func (r *GeminiChatRequest) SetTools(tools []GeminiChatTool) {
 }
 
 type GeminiThinkingConfig struct {
-	IncludeThoughts bool `json:"includeThoughts,omitempty"`
+	IncludeThoughts *bool `json:"includeThoughts,omitempty"`
 	ThinkingBudget  *int `json:"thinkingBudget,omitempty"`
 	// TODO Conflict with thinkingbudget.
 	ThinkingLevel string `json:"thinkingLevel,omitempty"`
@@ -183,7 +183,7 @@ func (c *GeminiThinkingConfig) UnmarshalJSON(data []byte) error {
 	*c = GeminiThinkingConfig(aux.Alias)
 
 	if aux.IncludeThoughtsSnake != nil {
-		c.IncludeThoughts = *aux.IncludeThoughtsSnake
+		c.IncludeThoughts = aux.IncludeThoughtsSnake
 	}
 
 	if aux.ThinkingBudgetSnake != nil {
diff --git a/dto/gemini_generation_config_test.go b/dto/gemini_generation_config_test.go
index ed4beb301943..bdc566371e84 100644
--- a/dto/gemini_generation_config_test.go
+++ b/dto/gemini_generation_config_test.go
@@ -87,3 +87,54 @@ func TestGeminiChatGenerationConfigPreservesExplicitZeroValuesSnakeCase(t *testi
 	assert.Equal(t, float64(0), generationConfig["seed"])
 	assert.Equal(t, false, generationConfig["responseLogprobs"])
 }
+
+func TestGeminiThinkingConfigPreservesExplicitFalseValues(t *testing.T) {
+	tests := []struct {
+		name string
+		raw  []byte
+	}{
+		{
+			name: "camel case",
+			raw: []byte(`{
+				"contents":[{"role":"user","parts":[{"text":"hello"}]}],
+				"generationConfig":{
+					"thinkingConfig":{
+						"includeThoughts":false
+					}
+				}
+			}`),
+		},
+		{
+			name: "snake case",
+			raw: []byte(`{
+				"contents":[{"role":"user","parts":[{"text":"hello"}]}],
+				"generationConfig":{
+					"thinking_config":{
+						"include_thoughts":false
+					}
+				}
+			}`),
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			var req GeminiChatRequest
+			require.NoError(t, common.Unmarshal(tt.raw, &req))
+
+			encoded, err := common.Marshal(req)
+			require.NoError(t, err)
+
+			var out map[string]any
+			require.NoError(t, common.Unmarshal(encoded, &out))
+
+			generationConfig, ok := out["generationConfig"].(map[string]any)
+			require.True(t, ok)
+			thinkingConfig, ok := generationConfig["thinkingConfig"].(map[string]any)
+			require.True(t, ok)
+
+			assert.Contains(t, thinkingConfig, "includeThoughts")
+			assert.Equal(t, false, thinkingConfig["includeThoughts"])
+		})
+	}
+}
diff --git a/relay/channel/gemini/relay-gemini.go b/relay/channel/gemini/relay-gemini.go
index e39826dd64e7..41a18e483adc 100644
--- a/relay/channel/gemini/relay-gemini.go
+++ b/relay/channel/gemini/relay-gemini.go
@@ -145,7 +145,7 @@ func ThinkingAdaptor(geminiRequest *dto.GeminiChatRequest, info *relaycommon.Rel
 					clampedBudget := clampThinkingBudget(modelName, budgetTokens)
 					geminiRequest.GenerationConfig.ThinkingConfig = &dto.GeminiThinkingConfig{
 						ThinkingBudget:  common.GetPointer(clampedBudget),
-						IncludeThoughts: true,
+						IncludeThoughts: common.GetPointer(true),
 					}
 				}
 			}
@@ -164,11 +164,11 @@ func ThinkingAdaptor(geminiRequest *dto.GeminiChatRequest, info *relaycommon.Rel
 
 			if isUnsupported {
 				geminiRequest.GenerationConfig.ThinkingConfig = &dto.GeminiThinkingConfig{
-					IncludeThoughts: true,
+					IncludeThoughts: common.GetPointer(true),
 				}
 			} else {
 				geminiRequest.GenerationConfig.ThinkingConfig = &dto.GeminiThinkingConfig{
-					IncludeThoughts: true,
+					IncludeThoughts: common.GetPointer(true),
 				}
 				if geminiRequest.GenerationConfig.MaxOutputTokens != nil && *geminiRequest.GenerationConfig.MaxOutputTokens > 0 {
 					budgetTokens := model_setting.GetGeminiSettings().ThinkingAdapterBudgetTokensPercentage * float64(*geminiRequest.GenerationConfig.MaxOutputTokens)
@@ -189,7 +189,7 @@ func ThinkingAdaptor(geminiRequest *dto.GeminiChatRequest, info *relaycommon.Rel
 			}
 		} else if _, level, ok := reasoning.TrimEffortSuffix(info.UpstreamModelName); ok && level != "" {
 			geminiRequest.GenerationConfig.ThinkingConfig = &dto.GeminiThinkingConfig{
-				IncludeThoughts: true,
+				IncludeThoughts: common.GetPointer(true),
 				ThinkingLevel:   level,
 			}
 			info.ReasoningEffort = level
@@ -271,10 +271,10 @@ func CovertOpenAI2Gemini(c *gin.Context, textRequest dto.GeneralOpenAIRequest, i
 							tempThinkingConfig.ThinkingBudget = common.GetPointer(budgetInt)
 							if budgetInt > 0 {
 								// 有正数预算
-								tempThinkingConfig.IncludeThoughts = true
+								tempThinkingConfig.IncludeThoughts = common.GetPointer(true)
 							} else {
 								// 存在但为0或负数，禁用思考
-								tempThinkingConfig.IncludeThoughts = false
+								tempThinkingConfig.IncludeThoughts = common.GetPointer(false)
 							}
 							hasThinkingConfig = true
 						default:
@@ -284,7 +284,7 @@ func CovertOpenAI2Gemini(c *gin.Context, textRequest dto.GeneralOpenAIRequest, i
 
 					if includeThoughts, exists := thinkingConfig["include_thoughts"]; exists {
 						if v, ok := includeThoughts.(bool); ok {
-							tempThinkingConfig.IncludeThoughts = v
+							tempThinkingConfig.IncludeThoughts = common.GetPointer(v)
 							hasThinkingConfig = true
 						} else {
 							return nil, errors.New("extra_body.google.thinking_config.include_thoughts must be a boolean")
@@ -308,7 +308,9 @@ func CovertOpenAI2Gemini(c *gin.Context, textRequest dto.GeneralOpenAIRequest, i
 							if tempThinkingConfig.ThinkingBudget != nil {
 								geminiRequest.GenerationConfig.ThinkingConfig.ThinkingBudget = tempThinkingConfig.ThinkingBudget
 							}
-							geminiRequest.GenerationConfig.ThinkingConfig.IncludeThoughts = tempThinkingConfig.IncludeThoughts
+							if tempThinkingConfig.IncludeThoughts != nil {
+								geminiRequest.GenerationConfig.ThinkingConfig.IncludeThoughts = tempThinkingConfig.IncludeThoughts
+							}
 							if tempThinkingConfig.ThinkingLevel != "" {
 								geminiRequest.GenerationConfig.ThinkingConfig.ThinkingLevel = tempThinkingConfig.ThinkingLevel
 							}
diff --git a/relay/channel/gemini/relay_gemini_usage_test.go b/relay/channel/gemini/relay_gemini_usage_test.go
index c8f9f834300c..6157f47ebc29 100644
--- a/relay/channel/gemini/relay_gemini_usage_test.go
+++ b/relay/channel/gemini/relay_gemini_usage_test.go
@@ -331,3 +331,38 @@ func TestGeminiTextGenerationHandlerUsesEstimatedPromptTokensWhenUsagePromptMiss
 	require.Equal(t, 100, usage.CompletionTokens)
 	require.Equal(t, 110, usage.TotalTokens)
 }
+
+func TestCovertOpenAI2GeminiPreservesExplicitFalseIncludeThoughts(t *testing.T) {
+	t.Parallel()
+
+	gin.SetMode(gin.TestMode)
+	c, _ := gin.CreateTestContext(httptest.NewRecorder())
+	c.Request = httptest.NewRequest(http.MethodPost, "/v1/chat/completions", nil)
+
+	request := dto.GeneralOpenAIRequest{
+		Model: "gemini-2.5-flash",
+		Messages: []dto.Message{
+			{Role: "user", Content: "hello"},
+		},
+		ExtraBody: []byte(`{
+			"google": {
+				"thinking_config": {
+					"include_thoughts": false
+				}
+			}
+		}`),
+	}
+	info := &relaycommon.RelayInfo{
+		OriginModelName: "gemini-2.5-flash",
+		ChannelMeta: &relaycommon.ChannelMeta{
+			ChannelType:       constant.ChannelTypeGemini,
+			UpstreamModelName: "gemini-2.5-flash",
+		},
+	}
+
+	converted, err := CovertOpenAI2Gemini(c, request, info)
+	require.NoError(t, err)
+	require.NotNil(t, converted.GenerationConfig.ThinkingConfig)
+	require.NotNil(t, converted.GenerationConfig.ThinkingConfig.IncludeThoughts)
+	require.False(t, *converted.GenerationConfig.ThinkingConfig.IncludeThoughts)
+}