Abstract: Presented in this paper is a 3-dimensional air-soil coupling model in which the assumption of static equilibrium is applied,where the air and soil are related through the mountain energy balance equation and that the effect of slope on sunshine and sunrise-sunset hour angles is taken into account.To promote model stability,sponge boundary condition and radiative boundary condition are adopted.Static deductive method is used to increase the model accuracy,too.The model is used to simulate the microclimate in Fangshan.The model result of the surface temperature and the air temperature of 1.5m height fit into the observed data very well.Moreover,the model is also used to simulate blocking,drainage flow,mountain and valley breeze,etc.And the several significance conclusions are obtained.