Abstract: In order to analyze the microphysical precipitation forming mechanisms of the‘0911’snowstorm in north China, the non-static mesoscale model ARPS (The Advanced Regional Prediction System) with detail microphysical processes was used to simulate the‘0911’-snowstorm in north China. Based on the study of the 39 microphysical conversion processes over 2 precipitation centers, it was found that Bergeron process and the deposition process of snow were 2 main microphysical precipitation mechanisms. The ice crystal conversion was abundant for natural seeding. The active degrees of Bergeron process and the deposition process are decided by the‘cnd’microphysical processes. The peak of the‘cnd’microphysical process stayed at the 6 km altitude during -15℃--20℃. In the range of temperatures, the difference between saturated vapor pressure on the water surface and on the ice surface conducted the peak. So the Bergeron process and the deposition process were very fierce at 6 km altitude. The special allocation of the temperature field and the microphysical processes was a key cause of the snowstorm.