Abstract: In order to study the characteristics and causes of heavy pollution in winter in Beijing, a typical heavy pollution process during the CPPCC (China People's Political Consultative Conference) in March 2018 was studied using radar remote sensing techniques such as boundary layer wind field, temperature/humidity field and aerosol vertical sounding. The results show that:(1) The pollution lasted for 7 d, including 118 h (69.8%) of slight pollution, 16 h (9.5%) of serious pollution, and the maximum pollution was 333.5 μg/m³. (2) The evolution of the pollution process is studied using the vertical observation equipment such as wind, temperature, humidity and aerosol. From the vertical spatial evolution of the aerosol, the formation of heavy pollution, in addition to the influence of the local source, has the external pollution transmission in the south and east of Beijing. The stable temperature layer of ground or upper temperature inversion is basically corresponding to the accumulation of PM_2.5 on the ground, in which the time of severe pollution is 68 h, the thickness is 500-1100 m, the maximum strength is 0.6℃/(100 m). The height of atmospheric boundary layer is low (the accumulation process is below 1000 m in the daytime and only 300-500 m at night), which leads to the continuous accumulation of pollutants. The near ground layer maintains a small wind and accumulates pollution; the high wind speed layer (about 10 m/s) in the southwest, east or southeast directions goes down to low altitude, which mitigates pollution, and the strong northwest wind or the north wind usually makes the pollution clear. The results show that the pollution process is closely related to the evolution of the meteorological elements in the boundary layer.