Today cities are the main habitat of human (homo sapiens) and they have profound effects on the biosphere. This changes have had undesirable consequences for human being such as degradation of environmental quality which ultimately would reduce the "quality of life" .Warming the urban environment is one of these unconscious effects of urban development that is called "urban heat island» (UHI) . Surface urban heat island causes warmer condition that can be is identified and analyzed using thermal Infrared Remote Sensing. Environmental planning could be partitioned in two steps: 1. analysis and explanation and 2. synthesis and prescription. In the first step, the given subjects are analyzed according to identified processes and problems. In the second step, according to the identified problems, solutions represent to improve the quality of the environment. i.e. “Environmental Assessment is Fundamental of sustainable environmental planning ". The main emphasis of this research has been on the assessment of the surface temperature of the urban environment. It should be noted that air temperature is different from surface temperature and each of which has different mechanisms. In this study, spatial distribution and changes in land surface temperature (LST) and vegetation index (NDVI) has been quantified in the urban region of Tehran using Landsat 7 ETM + image. Contrary to the expectations built-up areas has not highest temperature of surface, but open spaces. Gradient analysis of LST shows a reduction trend in north-east toward south-west of urban region of Tehran.