In order to investigate the possible mechanism of freezing rain process, the WRF model (Weather Research and Forecasting) was used to simulate a freezing-rain process occurred on 31 Jan 2013 in the area of the Beijing Capital International Airport. The NECP reanalysis data, the Black Body Temperature (TBB) of FY-2E, the daily average cloud height data of FY-3A are used to verify the model simulation. Major conclusions are as follows:1) The cloud top temperature of the simulation is consistent with TBB of FY-2E. During the freezing rain process, the cloud top temperature varied between 0--6℃, and the simulated vertical distribution of the hydrometeors agree well with observations. According to the cloud top height derived from FY-3A observations, it is found that the cloud top in the freezing-rain process basically remained at around 3 km, and the clouds contained less microphysical solid contents. 2) Observed cloud top temperature and height and the simulation results show that this is a typical warm freezing rain process. This result indicates that the mechanism for the formation of freezing rain in northern China may not be single. Ice-crystal processes and warm-rain processes may simultaneously exist during the formation of freezing rain.