Based on the NCEP/NCAR 1°×1° FNL data, satellite TBB data from Japan Meteorological Agency and dense surface observation data of China Meteorological Administration, this paper investigated a severe snow process in Southern Tibetan Plateau. The results show that (1) the snowstorm is mainly related to the impact from residual cloud systems of northwardmoving cyclonic storm phailin over the Bay of Bengal. (2) The southerly lowlevel jet between the storm and high pressure circulation is beneficial to the northward movement of Storm phailin and its impact. (3) The cyclone provides unstable energy via southerly lowlevel jet and the strong ascending airflows to Southern Tibetan Plateau, which creates favorable dynamic and thermodynamic conditions for the snowstrom. (4) The frontogenesis formed by the cold air from the westerly trough and warm air from the storm and the forced ascending caused by the terrain effect of Tibetan Plateau also enhance the dynamical conditions of snowstorm. (5) The unstable energy advection by the storm is the main energy source for the snowstorm. High elevation, dry and cold underlying surface and low 0℃ height over Southern Tibetan Plateau are important factors for the continuity of the snowstorm.