A CFD model (FloEFD) is applied to the wind field simulation around an isolated building in the Guyuan County Experiment Site.To obtain the optimal parameters of the model, a group of sensitive numerical experiments with different model parameters are carried out. The cavity length, vortex center, and the boundary location of the redevelopment area are used as the indexes to assess the outcomes.The results show that all the indexes are stable basically if the height of the computational domain is greater than 3〖WTBX〗h〖WTBZ〗 (the height of the building).The values of the indexes increase with the increasing levels of the initial mesh. All the indexes are not sensitive to the levels of local initial meshes. The vortex length before the building is more sensitive to the form of the mean wind profile than that after the building. By comparing to the observing data, the optimal parameters are: the height of computational domain being 3 times as high as building height, the level of the initial mesh being 4, the level of the local initial mesh being 4 and the form of mean the wind profile being exponential.