Abstract: On February 3,2024, a complex phase precipitation process with rare freezing rain, snow, hail and rainstorm in winter occurred in Guizhou. Based on the conventional meteorological observation data, FY-4A satellite cloud image, doppler weather radar data, the fifth-generation atmospheric reanalysis data of the European Centre for Medium-Range Weather Forecasts and the global assimilation forecast system model data from the China Meteorological Administration,the frontogenesis and instability mechanism of this precipitation process were studied by weather analysis and physical quantity diagnosis, and the model forecast error was analyzed.The results show that: (1)This weather process is a frontal precipitation weather formed by the development of southwest airflow in front of the south branch trough, the continuous strengthening of cold and warm air, and the interaction of Yunnan-Guizhou stationary frontogenesis. The mesoscale precipitation belt crosses the Yunnan-Guizhou stationary front, and the western section of the precipitation belt develops rapidly and violently. The precipitation echo has the characteristics of cumulus cloud echo, resulting in strong convective weather of hail and short-term heavy precipitation. In the eastern section of the precipitation belt, the weather is more stable and the precipitation intensity is weaker. The precipitation echo has the characteristics of stratified mixed echo, and the echo top extends higher with the development of ice crystal layer, resulting in the transformation of rain and snow phase. (2)The southwestern Guizhou in the western part of the precipitation belt is in the warm air mass in front of the stationary front. The rapid warming and humidification in the afternoon and the conditional static instability lead to the formation and development of vertical convection. The forecast error of the numerical weather model on the temperature and humidity conditions from the near surface to the lower layer of the atmosphere makes the static instability forecast weaker than the actual situation, which is an important factor causing the underreporting of hail weather in southwestern Guizhou. (3)The northeastern part of Guizhou in the eastern section of the precipitation belt is behind the stationary front, and the vertical distribution of temperature presents a three-layer model. Affected by the enhancement of cold air, the temperature of the whole atmosphere decreases, the melting layer weakens, the development of the cold layer and the ice crystal layer strengthens, the stationary front is generated, the condition symmetry is unstable, and the upward movement along the frontal zone is developed, and the precipitation changes from rain to snow. (4)The favorable temperature and humidity condition conversion of the model forecast is consistent with the actual situation, but the later duration is shorter than the actual situation, which is the main reason for the less snowfall forecast in northeast Guizhou.