In order to analyze the influence of different factors on the leakage and diffusion of the buried gas pipeline, the three-dimensional numerical model of the buried gas pipeline was established by using the software FLUENT based on the component transport model and the porous media model, and the influence of the internal pressure of the pipeline, the aperture of the leak port, the buried depth of the pipeline and the hardening of the ground on the leakage characteristics of the buried gas pipeline was analyzed. The results show that with the increase of the internal pressure of the pipeline, the leakage rate of the leakage port increases obviously, the leakage range in the pipeline direction is further, and the leakage in the atmosphere direction is more concentrated. The larger the aperture of the leakage port is, the greater the leakage amount in the same time, the larger the high concentration area near the leakage port, and the shorter the time to reach the boundary. With the increase of the buried depth of the leakage pipe section, the leakage methane reaches the surface later, the diffusion range is wider, and the methane content in the atmosphere is lower. The larger the width of hardened ground, the larger the obstacle area of methane leakage, most of the methane leakage in the soil, and the smaller the surface methane concentration and the diameter of the surface warning area. The influence weights of different factors on the dangerous area after the leakage of the buried gas pipeline are as follows: buried depth > hardening width > leakage aperture > internal pressure of the pipeline.