Abstract: Fuzhou was chosen as the study site, land surface temperatures were estimated form both ASTER images acquired on April 6, 2004 and Landsat TM image collected on June 15, 1989. Then the linear spectral unmixing-LSU model was used to estimate the vegetation abundances and percent of impervious surface from ASTER images. Before employing the LSU, the water body within the study area was masked and the C-terrain correction was applied to the images. Subsequently the NDVI image was also calculated using reflectance data of TM. With the inversion of land surface parameters mentioned above, the spatio-temporal changes of urban heat island (UHI) in Fuzhou from 1989 to 2004 were analyzed in various aspects. Comparisons between different methods used to determine the scopes of urban heat island showed that the mean-standard deviation method was more suitable for studying UHI than equal-interval method. Based on the researches discussed above, the dynamic changes of urban heat island were investigated and the spatial statistics technologies was then introduced, results indicated that after 15 years, the area extent of UHI was significantly enlarged and the urban heat intensity was also augmented, moreover, the standard deviation ellipse indicated that the center of UHI was moved towards southeast, which is in line with the planning policy of Fuzhou.