Based on a vinyl chloride leakage accident in a chemical plant, the affected area was analyzed by ALOHA software. The affected areas of toxic gas diffusion, vapor cloud explosion and boiling liquid expanding vapor explosion (BLEVE) were simulated. Google Earth was used to fit the hazard area of the leakage accident in the map. The results show that for the toxic gas diffusion accident, the first, second and third-level toxic areas are 1000~2500 m, 483~1000 m and 483 m of the downwind side, respectively. For the thermal radiation from vapor cloud explosion, the areas of the first and second warning line are 231 m × 200 m and 561 m × 280 m. The concentration of vinyl chloride within the third warning line is low and causes a small probability of explosion. The radii of red, orange and yellow warning lines of shock waves are about 214 m, 298 m and 621 m, respectively. For the BLEVE accident, people within 800 m of the vinyl chloride leaking tank has a fatal risk when exposed to thermal radiation. People within 1100 m of the tank may be burned. People within 2000 m of the tank will feel pain after exposed to thermal radiation for 60 s.