The application of CFD (Computational Fluid Mechanics) simulation is more and more extensive in the research field of urban air environment. CFD has its advantages on simulating the complicated air flow phenomenon and presenting intuitional descriptions. Planting work within a city has great ecological effect on city or district air environment, CFD simulation of planting effect on district air environment and its superiority for district air environment planning, the establishment of the model and its application for air environmental evaluation and improvement in district environmental management process is introduced and discussed in this paper. The significance and prospect of CFD simulation of planting effect for district planting planning is also demonstrated.