Abstract: Based on NCEP reanalysis data of 1 × 1 6h and conventional observation data,the circulation situation,physical quantity characteristics and configuration of upper and lower level jet streams of the two cooling and precipitation weather processes occurred in Liangshan state from December 28 to 30,2018 (process 1) and January 29 to 31,2019 (process 2) are analyzed comparatively. The results show that the two processes have the cooperation of upper air trough,cold air and south branch trough. The cold air path is the same,but the intensity is different,and the cold air in process 1 is stronger. Snowfall weather is closely related to 700hPa shear line and 0℃ isotherm. The water vapor in the two processes mainly comes from the Bay of Bengal,and the convergence of water vapor in the lower layer plays a major role in the water vapor in rainfall and snow weather. Both processes have certain ascending motion,both of which have the configuration of convergence at lower level and divergence at higher level,which is conducive to the vertical suction and the maintenance and development of ascending motion,but the ascending motion and high-low configuration of process 1 are better than process 2; The coupling of high and low level jet provides favorable power and water vapor conditions for the occurrence and development of precipitation.