A wireless relay anti-interference system includes a detecting module, a determining module, and a processing module. The detecting module detects a first received signal strength indication (RSSI), and a first carrier to interference noise ratio (CINR) of a first user. The determining module receives the first RSSI, the first CINR, and a first ratio between the first RSSI and the first CINR of first user, and determines whether the first user is entering a region of signal overlap. The method and system of the disclosure can avoid signal interference and improve the efficiency of the system.