Abstract: To study the regional air pollution and its causes of pollution,a serious heavy air pollution process was analyzed and simulated.Results show that pollutants cumulate for a long time and form heavy pollution with the high pressure and low weak pressure in the air,and regional air quality turns good in the influence of front.A meso-scale meteorology model is used to simulate relative meteorological factors. Simulation results can explain the mechanism of heavy pollution in northern parts of China.