Abstract: Coking project process is complex，and the environmental risk of the production process of coking is bigger． The present situation of the coking process environmental risk assessment exists some insufficient， such as standard selection and model selection， etc． The paper taking a 2. 4 million tons /year northwest coking project as an example， through the risk source analysis， the pollution meteorological conditions assumed and prediction model selection，analyzed and discussed the focus and technical key points of environmental risk assessment． The project determined the maximum credible accident for coarse benzene leakage diffusion and adopt AEGLs as risk standard and LC50 for comparison． Through the heavy gas model to predict， the results showed that the standard of LC50 calculation was significantly small and limited． According to the prediction，this project need risk prevention within the scope of project boundaries from 900 m to 1 990 m．