Abstract: The hard surface is one key factor of urban heat effect.The authors established a three-dimensional dynamic mathematic model by studying thermodynamic environment in Shenzhen City to simulate the temperature field in the case of the hard surface,and the simulating results accord with the monitoring temperature data perfectly.Furthermore,it is testified that hard surface owns more heat conduction and thermal storage and weaker hydraulic permeability than other surface and thus contributes more to the heat effect in the city and that the greenbelts could moderate the heat effect in the city.So the greenbelts should be arranged reasonably so as to improve micro heat environment in the city.