The layout of urban buildings is concentrated and the height of buildings is ultra-high. Leakage accidents of urban natural gas pipelines caused by third-party construction damage occur frequently, which may cause serious accident hazards in construction areas. Simulation of the diffusion after gas leakage between buildings is necessary. Based on the characteristics of various urban layout forms, this paper uses fluent software to simulate the leakage and diffusion of natural gas pipelines under four different building layouts. This paper explores the gas diffusion characteristics under different architectural layout, summarizes the danger zone. The simulation results show that the enclosed layout is the most dangerous layout among the four types of layout. Within the building complex, natural gas diffusion at the near end of the leakage source develops from the bottom up, while natural gas at the far end of the leakage source settles from the top down and accumulates under the influence of vortex. The blocking effect of the building on the diffusion of natural gas leads to the accumulation of natural gas on the windward side of the building wall, and the dangerous area of natural gas appears on the outside wall and the top of the building. This study is of great significance to guide the prevention and reduction of natural gas accidents.