Abstract: Using the ERA-interim reanalysis data and observation data,this study investigate the synoptic characteristics of the two cold wave events,with a focus on the conditions for formation of large snowfall.The results showed that the two cold wave events occurred after the days with higher-than-normal temperature,and are accompanied by a strong trough and ridge at the middle and high latitudes in Eurasian at 500hPa,cold air accumulated in the middle Siberia,while these features are clearly different between the two cold wave events.There is a strong trough located to the south of the Tibetan Plateau for the two cold wave events,with different strength,speed and life time.The two events share some common features:the strong southwesterlies at the eastern part of the trough to the south of the Tibetan Plateau transport large amount of tropical warm and moist air to the Sichuan Basin when it moves eastward to the 85° E,causing precipitation by converging with the cold and dry air outbreak from Siberia.Temperature in the Sichuan Basin drops quickly after rainfall.Due to the quick decrease in temperature,rainfall shifts to snowfall when the air temperature at 850hPa, 1000hPa and 940hPa levels is lower than-5℃, 4℃and 0℃.