Abstract: With the diagnosis analysis method of wave packet propagation(WPD),by using the NCEP/NCAR reanalysis data of height field,we study the distribution characteristic of wave packet and propagation characteristic of wave energy based on a widespread snow storm event in southern marginal and east-central areas of Tibet on 19-23 October,2005.The results show the distribution characteristic of wave packet and the propagation characteristic of wave energy in middle level 500hPa can show the snowstorm process better which occurred during that period.We can see the snowstorm process appear in the high value region of wave packet and the outbreak & extinction of the process.The distribution characteristic of wave packet is in accordance with the process of severe convection weather.The movement path of wave packet can perfectly display the propagation of accumulated perturbation energy.Accordingly,the process can be recognized as three cycle of "accumulation-release" which happened in Oct.21st²3rd.