Abstract: In order to scientifically predict the hazard scope of explosive hazard area which is formed by the natural gas diffusion between parallel buildings, this paper established the functional relation between natural gas leakage rate and time. Then, the influence of leakage pressure and building layout on the explosive hazard area was clarified using the transient simulation method. The simulation results show that when the natural gas meets a building in the process of diffusion, it will form a sub-diffusion center in the leeward direction and then diffuse around. With the increase of its height from the ground, its maximum volume fraction decreases gradually and reaches a stable value as the leakage continues. The buildings upwind are dangerous in all operating conditions while the danger of the buildings downwind is temporary (except for small building spacing conditions). Under the wind conditions, increasing the building spacing, reducing the relative height of parallel buildings and lowering the operating pressure of the pipeline are all conducive to the diffusion of natural gas between two buildings. The research results can provide the scientific basis for the formulation of relevant regulations and the prevention of accidents.