According to the characteristics of the canteen, the FLACS software was used to build a three?dimensional model for a university canteen. On the basis of considering the jet direction, obstacles and other factors, the leakage and explosion of natural gas were simulated, and the diffusion process of gas cloud, the development law of explosion shock wave and temperature in a specific scene were studied. The results show that when the gas leaks vertically upward, the gas accumulates in the small booth due to the obstruction of the canteen roof. When the natural gas leaks horizontally, the volume fraction of natural gas cloud in the dining area is higher. At the initial stage of the explosion, the explosion pressure shock wave centered on the ignition point first appears, and the pressure shock wave travels outward in a circular arc. The leakage direction has little effect on the maximum over pressure generated by the explosion.The temperature distribution is greatly affected by the direction of leakage. When vertical injection is carried out, the high temperature is concentrated in the small booth. When horizontal injection is carried out, the temperature is distributed from high to low.