Abstract: In order to fast assess the environmental risks of emergency leakage from the distillation columns in petrochemical enterprises, the diffusion results of crude oil vapor under both calm and windy conditions were obtained and then visualized by applying the software MATLAB based on hazardous substance leakage and diffusion models. Under the two types of meteorological conditions, the maximum concentrations of the released crude oil vapor were found at release source and at the point in the distance of 1 200 m from the release point respectively. The figures of concentration contours were obtained based on simulating calculations. In the possible explosion areas, the facilities around the explosion sites could be on fire or deformed because of overpressure, and the atmospheric environment over the explosion sites would be polluted. People in different radius ranges of overpressure would be damaged by different degrees. People would all get to death within a radius of 90.3 m of explosion accident and would be heavily injured within a radius of 145.4 m. The alkane from incomplete combustion of the explosion accidents and the crude oil vapor beyond the explosion areas would also have some adverse effects on the people’s health and the surrounding environment.