Abstract: A typhoon numerical model with horizontally threefold structure has been developed based on the MM4 model introduced from PSU/NCAR. The model was constructed of the inner, middle, outer regions with three kinds of different resolutions, respectively, and the double-way boundary feedbacks are also available between the different regions of the model. Integral physical processes are considered in the model including the effects of mountains and surface frictions, diffusions of momentum, heat and water vapor, effects of latent and sensible heat at the earth’s surface, effects of cloud and radiations and cumulus convection. The studies and the operational application results have shown that the model can predict not only the landing and recurvature tracks of typhoon and their circulation changes, but also the locations and intensities of the typhoon centers, the total rainfall amount, the rain areas and its expansion in the different typhoon processes.