The relationship between the snow cover of the Qinghai-Tibet Plateau and the temperature and precipitation in summer in Yunnan Province is studied.The Result shows that the peak of annual array of depth of snow cover corresponds to the low temperature of Yunnan in summer and that the more the snow cover,the more the precipitation in June at Kunming in July at the most of Yunnan and in August North East of Ailaoshan mountain range.The analyses of 500hPa circulation show that during more snow cover year cold air activities are strengthened in Yunnan.