Abstract: ALOHA software and the Gaussian Plume Model were utilized as the basis to analyze the impact of various factors on the spread distance of hazard zones through the setting of leakage accident scenarios. And the diffusion influence under worst-case conditions was analyzed. The results show that larger leakage apertures and higher atmospheric stability levels result in farther diffusion distance of different hazard zones; and higher height of leakage point, greater wind speeds and greater surface roughness reduce the spread distances of these zones; wind speed and atmospheric stability demonstrate stronger sensitivity in influencing diffusion distances; under worst-case conditions, residential buildings 150m downwind of the station fail to meet minimum safety distances, exposing outdoor personnel in this vicinity to a certain injury risk. The research results can provide a theoretical basis for the rapid and reasonable division of the alert areas，to ensure the safe and stable operation of gas transmission stations.

Key words: ALOHA, gas transmission station, leakage diffusion, Gaussian plume, natural gas