The mesoscale WRF model is used to simulate Typhoon MANGKHUT (2018) with high spatial resolution, and the fine dynamic structure and rainband characteristics of the typhoon are analyzed on this basis. The results show the dynamic configuration of low-level radial inflow and high-level radial outflow exists at the eye wall of Typhoon MANGKHUT, and there are high-value area of tangential wind speed and vertical ascending area near the eye wall, which incline outward with the height. The radar echo is strong and the convective system is deep near the eye wall. The disturbance field of vortex Rossby wave is obtained by scale separation method and the characteristics of vortex Rossby wave in the typhoon are analyzed. It is found wave 1 and wave 2 propagate in both tangential and radial directions, the amplitude of wave 2 is significantly smaller than that of wave 1, and the high-value area of positive vorticity disturbance of wave 1 and wave 2 basically covers the area of strong radar echo accompanied with strong convections; in the vertical direction, when the vorticity disturbance of the precipitation area is positive in the high level and negative in the low level and the divergence disturbance is vertically in the similar configuration, the convective systems will be strengthened, which is favorable for the enhancement of precipitation. Thus it can be seen that the dynamic configuration of high-level divergence and low-level convergence of the disturbance of wave 1 and wave 2 can promote the development of convective systems and has certain effect on the intensity and distribution of typhoon precipitation.