Abstract: Numerical method was adopted in this paper to simulate the migration of petroleum contaminants in the phreatic aquifer using the data from an electric factory of Xinjiang. Simulating results show that the main direction of migration of petroleum contaminants is same as the shallow groundwater. Diffusion, however, may cause the leakage of contaminants. The dispersion of petroleum concentration follows a normal distribution pattern. At the place 400 meters far from the pollution source, the concentration of contaminants may reach 0.16 mg/L within 9 years. The pollution speed gradually increased in the beginning and decreased at last, but the leakage of petroleum was increasing gradually. It is estimated that the influence of petroleum contaminants may expanded up to an area of 36 400 m² in about 20 years. The maximum migration distance may reach 1 297 m, which exceeds the groundwater migration distance.