Abstract: Poisonous gas leakage accidents seriously threaten the safety of people’s lives. Based on simulation, it is of great significance to explore the precise evacuation of personnel in chemical plant leakage accidents to ensure the safety of personnel in the field. The PHAST software was used to analyze the distribution range of liquid ammonia leakage danger areas under different wind direction conditions, and the emergency evacuation simulation of personnel was carried out through pathfinder software. Taking the emergency evacuation of liquid ammonia leakage accident in chemical plants as an example to determine the regional boundary and effective early warning release time of evacuation risk, and the safety of the evacuation path scheme under different wind direction conditions was studied and judged, and the optimization scheme of the evacuation path of leakage accident in different scenarios could be proposed. The simulation verification and effect analysis were carried out. The results of the calculation analysis show that the effective warning release time after liquid ammonia leakage of the plant should be within 8.1s. It takes 168s to evacuate personnel before path optimization. After optimization, the evacuation time is shortened by 43s, and the evacuation route simulation using PHAST and Pathfinder software can provide a reliable basis for optimizing the evacuation route and effectively improve the evacuation safety.