The ambient fields for much high wind and hail were analysed by the atmoshpere general circulation,humidity front,high and low level jet and kinetic energy of vorticity and divergent components over south Yunnan in spring in 1997. The new knowledge about the variations of south trough in westerlies,humidity gradient in low level,jet and perpendicular velocity,and kinetic energy of vorticity and divergent components were obtained and the results are valuable in forecasting.