Landsat thermal images were used to study the urban heat island effect of Quanzhou City during its urbanizationperiod from 1989 to 2000. The result shows that the area of heat island is increasing along with urban expansion, and thetrend is the same as that of urban expansion. The seasonal difference makes the comparison of the thermal image data verydifficult. In order to solve this problem, the authors processed different thermal infrared bands one by one with the helpof image normalization technology. The intensity and the spatial structure of the urban heat island effect were investigated by means of landscape analysis. It is shown that agglomerate, circularity and fragment are three basic configurations of the heat island in Quanzhou City. The cause of the urban heat island is discussed and the effective measures are suggested to tackle the urban heat island effect.