The invention relates to a method for preventing mine gas from exploding and an implementation device thereof. The invention utilizes the excellent characteristic that gas rapidly rises to the top of a roadway without ventilation because the gas is suffered from buoyancy in air, and flows outwards along the top, and thereby, explosible gas-air mixed gas can not be formed at 2/3 height of the roadway, and therefore, the gas can not explode when a combustion source exists. Accordingly, a first sensor (1) for monitoring alarm methane concentration and outage methane concentration is arranged near a working face (6), and a second sensor (2) for monitoring air supply off/on critical methane concentration is also arranged; air supply is stopped when the methane concentration is not less than 3.2 percent, and ventilation is carried out when the methane concentration is less than 3.2 percent; a third sensor (3) for monitoring evacuation methane concentration is arranged; a worker evacuation signal is sent out when the methane concentration is not less than 50 percent; an automatic controller (4) completes control according to the signal of each sensor, and an evacuation notifier (5) sendsout an evacuation notification. The invention realizes that the air supply is stopped at the initial stage of gas discharge and explosion can not happen at the 2/3 height of the roadway even with sparks; and when in ultra high gas emission, workers evacuate in time and escape from a shaft safely.