diff --git a/main/application.cc b/main/application.cc
index 9bccaef1..1fd0214f 100644
--- a/main/application.cc
+++ b/main/application.cc
@@ -383,10 +383,12 @@ void Application::Start() {
                 protocol_->server_sample_rate(), codec->output_sample_rate());
         }
         SetDecodeSampleRate(protocol_->server_sample_rate());
-        // IoT device descriptors
-        last_iot_states_.clear();
         auto& thing_manager = iot::ThingManager::GetInstance();
         protocol_->SendIotDescriptors(thing_manager.GetDescriptorsJson());
+        std::string states;
+        if (thing_manager.GetStatesJson(states, false)) {
+            protocol_->SendIotStates(states);
+        }
     });
     protocol_->OnAudioChannelClosed([this, &board]() {
         board.SetPowerSaveMode(true);
@@ -789,9 +791,8 @@ void Application::SetDecodeSampleRate(int sample_rate) {
 
 void Application::UpdateIotStates() {
     auto& thing_manager = iot::ThingManager::GetInstance();
-    auto states = thing_manager.GetStatesJson();
-    if (states != last_iot_states_) {
-        last_iot_states_ = states;
+    std::string states;
+    if (thing_manager.GetStatesJson(states, true)) {
         protocol_->SendIotStates(states);
     }
 }
diff --git a/main/application.h b/main/application.h
index f0aa8b83..63a5230c 100644
--- a/main/application.h
+++ b/main/application.h
@@ -91,7 +91,6 @@ private:
     bool keep_listening_ = false;
     bool aborted_ = false;
     bool voice_detected_ = false;
-    std::string last_iot_states_;
     int clock_ticks_ = 0;
 
     // Audio encode / decode
diff --git a/main/iot/thing_manager.cc b/main/iot/thing_manager.cc
index 9c1c11e3..92438697 100644
--- a/main/iot/thing_manager.cc
+++ b/main/iot/thing_manager.cc
@@ -22,16 +22,32 @@ std::string ThingManager::GetDescriptorsJson() {
     return json_str;
 }
 
-std::string ThingManager::GetStatesJson() {
-    std::string json_str = "[";
+bool ThingManager::GetStatesJson(std::string& json, bool delta) {
+    if (!delta) {
+        last_states_.clear();
+    }
+    bool changed = false;
+    json = "[";
+    // 枚举thing，获取每个thing的state，如果发生变化，则更新，保存到last_states_
+    // 如果delta为true，则只返回变化的部分
     for (auto& thing : things_) {
-        json_str += thing->GetStateJson() + ",";
+        std::string state = thing->GetStateJson();
+        if (delta) {
+            // 如果delta为true，则只返回变化的部分
+            auto it = last_states_.find(thing->name());
+            if (it != last_states_.end() && it->second == state) {
+                continue;
+            }
+            changed = true;
+            last_states_[thing->name()] = state;
+        }
+        json += state + ",";
     }
-    if (json_str.back() == ',') {
-        json_str.pop_back();
+    if (json.back() == ',') {
+        json.pop_back();
     }
-    json_str += "]";
-    return json_str;
+    json += "]";
+    return changed;
 }
 
 void ThingManager::Invoke(const cJSON* command) {
diff --git a/main/iot/thing_manager.h b/main/iot/thing_manager.h
index b212c3dc..d51c910b 100644
--- a/main/iot/thing_manager.h
+++ b/main/iot/thing_manager.h
@@ -25,7 +25,7 @@ public:
     void AddThing(Thing* thing);
 
     std::string GetDescriptorsJson();
-    std::string GetStatesJson();
+    bool GetStatesJson(std::string& json, bool delta = false);
     void Invoke(const cJSON* command);
 
 private:
@@ -33,6 +33,7 @@ private:
     ~ThingManager() = default;
 
     std::vector<Thing*> things_;
+    std::map<std::string, std::string> last_states_;
 };
 
 
diff --git a/main/protocols/protocol.cc b/main/protocols/protocol.cc
index b2c079f7..5b8c9a29 100644
--- a/main/protocols/protocol.cc
+++ b/main/protocols/protocol.cc
@@ -95,7 +95,7 @@ void Protocol::SendIotDescriptors(const std::string& descriptors) {
         cJSON_AddItemToArray(descriptorArray, cJSON_Duplicate(descriptor, 1));
         cJSON_AddItemToObject(messageRoot, "descriptors", descriptorArray);
 
-        char* message = cJSON_Print(messageRoot);
+        char* message = cJSON_PrintUnformatted(messageRoot);
         if (message == nullptr) {
             ESP_LOGE(TAG, "Failed to print JSON message for IoT descriptor at index %d", i);
             cJSON_Delete(messageRoot);
@@ -111,7 +111,7 @@ void Protocol::SendIotDescriptors(const std::string& descriptors) {
 }
 
 void Protocol::SendIotStates(const std::string& states) {
-    std::string message = "{\"session_id\":\"" + session_id_ + "\",\"type\":\"iot\",\"states\":" + states + "}";
+    std::string message = "{\"session_id\":\"" + session_id_ + "\",\"type\":\"iot\",\"update\":true,\"states\":" + states + "}";
     SendText(message);
 }