diff --git a/README.md b/README.md
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--- a/README.md
+++ b/README.md
@@ -1,2 +1,4 @@
 # kc868-arduino-library
 This library is designed for KC868-H32B Pro Smart Controller. Enable KC868-H32B Pro in "Development mode", then you can write arduino code download to ESP32 to read/write 32 channel relay and 6 digital digital input ports.
+
+# [API_Reference](https://github.com/hzkincony/kc868-arduino-library/blob/main/API_Reference_EN.md)