The geographical spatio-temporal heterogeneity is a conspicusous characteristic in mountainous region. Its research visualized the complicated geographical patterns and processes, and promoted quantitative analysis in geography. The vegetation regional difference is calculated by raster calculator bar in ARCGIS, with MODIS-EVI as vegetation index in this study. Rainy season starting of 2001 is quantified from their precipitation variatons, including 30 data attracted from meteorological stations in southern Yunnan Province. The results show that: (1) the spatio-temporal difference of vegetation landscape is very remarkable, for EVI value shows higher averagely and variation slower down or up seasonally in the western of Wuliang Mt.-Ailao Mt. assemblage zone than in the eastern region; (2)there are serious differences in EVI vulue of different directions between these two regions at the end of April or early May. The vegetation coverage of the eastern region presents increase firstly in the middle of April of 2001, but with time going, its increase degree becomes weaker and weaker obviously than that in the western region; (3) the regional distinction is obvious in 2001 for the beginning time of rainy season is earlier with ten or fiffteen days in the eastern region. In one word, the Wuliang Mt.-Ailao Mt. assemblage zone becomes a boundary zone in the climatic characters and vegetation patterns, as the result of the effect for the high mountains on barrier or interception of vapor transportation.