Abstract: A fitting function for the unsteady wind velocity based on the data measured several seconds apart is firstly developed,and the 3D structure of a real complex terrain in a wind farm is established according to the digital elevation model. Then,using the LatticeBoltzmann method（LBM）incorporated with the adaptive mesh refinement method,the unsteady flow field induced by the complex terrain is simulated and the distribution of wind energy resources is obtained. After that,the 2 MW wind turbines are sit in the wind farm and the full scale flow field induced by the terrain and wind turbines is simulated considering the rotating of blades. The wake structure of wind turbines in the complex terrain and under the unsteady inflow is investigated. The results show that the present modeling framework can be used to predict the wind resource distribution on the complex terrain considering the inflow velocity fluctuation,and achieve the multiscale simulation in a wind farm with considering the wake structure of wind turbines.