Abstract: Based on the surface meteorological data and T639 numerical model forecast data,the high-resolution convective available potential energy was calculated.And it was used to analyses once severe convection weather case occurred in Yunnan province during August 5 and August 6,2012.The results show that there is strong convective instability energy distribution over most area of Yunnan before the severe convective weather occurred.Severe convective weather occurred mainly in the areas of the CAPE above 2000J/kg.the strong CAPE appears early than the strong convective clouds for 3—5 hour.After the strong convective clouds generated over the areas of the CAPE high value,it has a trend of flowing to the downwind direction of steering flow.This analysis method can give an unstable energy distribution with higher spatial resolution in each hour,and is of certain indicating significance for short-term forecasting of severe convective weather.