Abstract: CFD method has the advantage of well simulating the flow over wind farm of complex terrain,compared with the method of using the software WAsP with linear model, thus becoming the development direction of assessment of wind resources in complex terrain. In order to use the CFD package FINE/TURBO and standard k-ε turbulence model with wall function in the wind resources assessment and micrositing of wind farm in the complex terrain, in this paper, Island Nanao had been simulated in wind directions at intervals of 30 degrees,under the assumption of neutral condition, to investigate the influence of inlet condition on the results. The simulation results show that the wind speed-up and intensity don't change essentially under different inlet conditions. Based on this law, with whole year wind data, an assessment method with post processing has been built, providing a strong reference for engineering practice.