Abstract What kind of high density urban form presents a better micro-climate environment in summer days is the main question of this study. The micro-climate of three different urban form were simulated using the software ENVI-met. Parameters including building density, floor area ratio, green plot ratio, pavement area, building height are concerned in the simulation. By comparing and analyzing the air temperature (Ta), solar radiation, mean radiation temperature (Tmrt) and wind speed, the micro-climate performance in three cases are presented. The alternative thermal index physiological equivalent temperature (PET) is also used to evaluate the outdoor thermal comfort in the three cases.