Abstract: As one of the most suitable analysis tools for urban climate research, CFD simulation technology requires huge computational overhead that a microcomputer is generally hard to provide. In order to reduce computational overhead, the scaled model was introduced into the CFD simulation of urban climate based on the similarity theory. In the proposed method, a virtual flow medium was constructed according to the equivalence of each similitude criterion number between the scaled model and its prototype, and the similar boundary conditions were also given out, thus it ensured the similarity results. The proposed method was verified and analyzed by the CFD simulation of atmospheric flow within a residential district. It is demonstrated that the CFD scaled simulation is in good agreement with the full-scale model for both flow patterns and accuracy. At the same time, the computational overhead is reduced effectively. The proposed model is not only suitable for urban atmospheric flow, but also helpful for the development of scaled simulation in other large-scale engineering applications.