Abstract: This study developed an improved model for the dispersion of released toxic gases based on the widely used model SLAB. A major improvement enhanced the model's ability to represent observations. SLAB was upgraded to account for temporal variation in wind vectors. In the method,the gas diffusion process was divided into several time intervals,and the algorithms of coordinate rotation and coordinate translation were used to make real-time changes in meteorological conditions which should be considered in dispersion forecasting. Theoretically,the results of improved SLAB better reflect the true conditions. Thus,the improved model can provide decision makers with timely and accurate guidance,so as to minimize hazards to people and the environment.