Abstract: Unsteady compressible Reynolds-averaged Navier-Stokes equations in absolute coordinate system are solved to simulate the flow field which is affected by propeller slipstream in turbopro airplane takeoff states. A moving overlap grids technology is used to depict the relative motion of propeller blades. In order to guarantee the time precision and enhance computing efficiency, a fully implicit dual-time stepping method and multigrid scheme are used in parallel environment. The aerodynamic performance of airplane with propeller slipstream from numerical calculation agrees well with the experimental data. The results show that, the dynamic pressure of the flaps in the slipstream region is obviously increased, at the same time, because the slipstream blows away the accumulated boundary layer on the flaps, the slipstream delays the separation of the airflow on the flaps. These two factors mentioned above significantly improve the efficiency of the flaps, in addition, through the guide function of the flaps, the wash of the slipstream flow on the flaps is not as obvious as that on the wings. The acceleration effect boundary of the slipstream is acquired by local dynamic pressure increments and the wash effect boundary of the slipstream is gotten by local airflow angle increments. With this method, the non-linear phenomenon of the stability of the propeller aircraft, due to the interference effect of slipstream on air-craft components, can be well captured and explained. Also, the slipstream's wake convection and evolution can be revealed by the method. The present work provides certain reference for both propeller aircraft design and slipstream effect research.