Abstract:Temporal and spatial distributions and its geographical causes of the heat index at 125 stations in Yunnan From 1971-2003 were analyzed by the PCA method,statistic analysis and the non-integer technique of power spectrum.The results show that(1)the barrier and passage effects of longitudinal range-gorge break the law of zonal distribution of air temperature in Yunnan,the law of longitudinal distribution of air temperature is obvious and the spatial distribution is very zonally asymmetry;(2)under the effect of longitudinal range-gorge,the distributive pattern of thermal resources in Yunnan is that heat resources are abundant in the south area of Yunnan,deficient in the north area,more abundant in the west area than the east area,with the most abundant in the river valley regions and the poorest in the northwest area and mountain areas;(3)heat resources are the most abundant in June and July each year in Yunnan,the poorest in January,and in-between in spring and autumn with the former's greater than the latter's;(4)Yunnan annual mean temperature has obviously increasing trend with obvious 7a,11a,18a and weak 3a,5a periodic oscillations during the past 30-year;(5)the PCA1 of annual mean air temperature in Yunnan shows the same change trend over the most areas but the PCA2 displays opposite trends in the east and west areas,respectively.