The land surface Temperature(LST) and vegetation index were derived from EOS/MODIS data, and the high resolution LST was corrected by AWS(automatic weather station) data according to a new variational processing method, the character of the urban heat island(UHI) of Changsha and its causes are investigated. By the study of the relationship between vegetation and spatial characteristics of UHI, the mainly spatial characteristics of UHI has been analyzed and it was: (1) The terrain of the suburbs is higher than the urban region, the gradient of the terrain height is small, and this geomorphological featrue is conducive to assemble of the heat, the UHI phenomenon of Changsha is obvious especially in the summer night; (2) The UHI distribution is similar to the outline of the urban construction. The LST of urban is 3─5 ℃ higher than the flat low areas close around the city, and 6─8 ℃ higher than further areas. The region which has the most obvious UHI phenomenon is the region surrounded by the second city ring road, and the UHI phenomenon gradually weakened from the city centre to suburb; (3) The impact of geomorphological character to UHI is notable, the relationship between vegetation index and UHI is Anti-related, it was indicated that the improvement of the vegetational status is very important to the elimination of UHI phenomenon, the implementation of the urban green land planning can reduce UHI effect.