Node localization is becoming a hotspot in international research of WSN (Wireless Sensor Network) nowadays. Distance measuring, as the core of all location algorithms, may cause large range error. RSSI??Received Signal Strength Indication??, one of the common methods of distance measuring in WSN node localization, is very sensitive to the environment, thereby it causes great range error. The antenna diversity technique, mostly used to enlarge the capacity of channels and expand the cover range of the signal in order to improve the quality of the transmission signal, is applied in the WSN node localization. Compared with the traditional RSSI distance measuring, the location accuracy is effectively improved.