In this study, characteristics and variations of Heat Island Potential (HIP) on urban blocks were examined from a viewpoint of land use and countermeasure for thermal environment in order to obtain knowledge about the influence factor on sensible heat flux from all surface of urban blocks. First, four types of land use, commercial/business, residential, industrial and main road, were selected for analysis. All surface temperature and HIP of urban block was calculated by heat balance simulation at 28 cases on clear sky day in summer. It was clarified that HIP of each model was different characteristically, and material of urban block, planting method and room temperature of building influenced largely on that. Especially, drop of HIP by tall trees planting was remarkable.