Retrieving the land surface temperature by hdf data in MODIS receiver system, first the few cloudy data were selected, and then cloud be removed by means of multiband combination. The average temperature figures of Yangtze Delta were retrieved by split window algorithm, the distribution characteristics of Yangtze Delta area were analyzed, and the heat islands are arranged in “Z” distribution. In Yangtze Delta area, the heat island intensity is the strongest in summer, then in spring and most areas are in weak or no heat island except few areas in strong heat island in winter. By GIS geographic statistics, the strong heat island areas were compared. And the change trend of heat island of each city from 2001 to 2008 were also being analyzed. The data were processed in Delphi and IDL languages including data projection, inversion, cartography. The analysis of island heats was independently conducted, and average retrieval results were more objective.