Abstract: Based on the 5-level primitive equation model designed by Shanghai Typhoon Institute, in this paper a 5-level nested mesh scheme is presented, in which the coarse-mesh area is fixed and the fine-mesh area is changeable. Methods for conjunction and adjustment of dependent variables are used at the juncture of the coarse-mesh and the fine-mesh. It is shown from numerical experiments that there exists better penetrability at the boundary of the fine-mesh area, and the pattern and intensity of the predicted pressure systems in the inner fine-mesh area are improved.