The invention relates to a 500kV transformer fire alarm system based on wireless passive temperature sensors. The system includes three transverse tracks and three longitudinal tracks respectively arranged on the front side face, the rear side face, the left side face, the right side face and the top face of a 500kV auto-transformer. Multiple wireless passive temperature sensors are arranged on each track in the three transverse tracks and the three longitudinal tracks. The wireless passive temperature sensors match wireless passive temperature sensor terminal controllers. The wireless passivetemperature sensor terminal controllers receive data collected by the wireless passive temperature sensors, and transmit the data to a fire control screen. The fire control screen matches a master control computer and a secondary control protection screen. According to the 500kV transformer fire alarm system based on wireless passive temperature sensors presented by the invention, the wireless passive sensors are arranged on the three transverse tracks and the three longitudinal tracks, and the body temperature of the transformer can be reflected in an all-round way.