Abstract: Based on 500hPa geopotential height field from T63 dynamical extended range forecast products,the observed precipitation data of Yunnan,and NCEP／NCAR reanalysis data(500hPa),the March—August precipitation forecast skills in Yunnan have been studied by using the downscaling method.The precipitation anomaly average ratio between the reconstruction and the observation in March—August are all over 60%.The proportion of years that the correlation coefficients between the reconstruction and the observation through α=0.05 reliability testing are all over 65%.In the light of this approach,the precipitation in March—August of Yunnan from 2005 to 2007 was prospected.The results show that downscaling method predictions can reflect the March—August pentad precipitation spatial and temporal distribution and its evolution trend.The relationship between general circulation and regional rainfall has been explored from the perspective of statistical-dynamical downscaling.The approach is of obviously dynamical background and weather study significance.