Abstract: Based on Navier-Stokes equations with multi-block structural grids, CFD software TRIP3.0 is performed to compute the drag for the DPW4 wing/body/tail configuration. SST two-equation turbulence model is employed for the simulations of turbulent flows. The effects of mesh density and Mach numbers on the aerodynamic characters and pressure distributions are carefully studied. The present numerical results are in good agreement with the arithmetic mean values provided by DPW4. It is demonstrated that mesh density have some influence on total drag, and influence on pressure drag is observed, whereas various grids have little influence on pressure distribution. The analysis of the difference between the present paper and the wind tunnel test needs additional research work.