The analysis of the synoptic situation and physical quantity field With the MI-CAPS's routine data on 3? March,2005 shows that the cold wave moved from north to south,and then moved from east into west and northwest of Yunnan.Because there was maintained strong anticyclonical circulation all along from the Bay of Bengal to Indochina Peninsula,and the anticyclonical centers were all stronger in the upper,middle and lower at-mosphere,the cold wave was obstructed and couldn't move to the south.There was no southern branch trough coupling,but the lower trough south of the plateau offered plentiful water vapor for the snowfall and rainfall,the northwest current at SOOhPa brought strong cold advection.The 200hPa shear line that kept in Lijiang,Kunming and Mengzi was the main dynamical factor for snowfall and rainfall weather.