Abstract: Dangerous chemicals leakage and diffusion accidents occur occasionally in the chemical plant.The key to dealing with such accidents is to confirm the location and rate of leakage sources quickly and accurately.Aiming at the defects of traditional leakage source inversion method，which is time-consuming and low accuracy，this paper proposes a leakage diffusion accident inversion method based on chicken swarm optimization （CSO） algorithm.This method takes the error between the gas concentration data monitored by the gas sensor and the calculated value of the model as the optimization objective.It transforms the inversion problem of hazardous chemical leakage and diffusion accident into an optimization objective minimization problem，and solves this problem with the chicken swarm optimization algorithm.In order to improve the accuracy of the algorithm，a weighted centroid method is used to construct a high quality initial solution set，which achieves an accuracy of 1m.The simulation results show that the chicken swarm optimization algorithm can accurately find the leakage source location in a short time，and its robustness can meet the actual demand; and that the method can realize the rapid and accurate positioning of hazardous chemical leakage sources in the chemical park and the accurate estimation of the strong leakage sources，thus providing timely and effective support for emergency decision-making.

Key words: hazardous chemicals, leakage, gas diffusion model, leakage source inversion, chicken swarm