The invention provides a WiFi relay communication system applied to Mars detection, which comprises surrounding device WiFi communication unit, a lander WiFi communication unit and a propeller WiFi communication unit, wherein the surrounding device WiFi communication unit and the lander WiFi communication unit are in bidirectional communication, and the surrounding device WiFi communication unit and the propeller WiFi communication unit are in bidirectional communication. The WiFi relay communication system provided by the invention adopts miniature and modularized device, meets requirements of miniaturization, low power consumption and low weight of equipment of a deep space detector, and has the technical characteristics of high integration level, good reliability, high universality and expansibility and the like. The WiFi relay communication system can be applied to follow-up developed detectors of Mars detection, and can also be applied to other deep space detection aircrafts having similar requirements.