The aim of numerical experiment of ram air turbines is mainly to simulating its adjustable-pitch aerodynamic characteristic on the actual flight-refuel conditions. The Baldwin-Lomax turbulence model and the Reynolds-averaged Navier-Stokes were used to simulate the 3-D internal and external mixed flow fields. The present paper also discussed the cause of load distributing on the blade surface and analyzed the main aerodynamic characters of the turbine flow fields. The simulation results were compared with the experimental results of wind tunnel. It was pointed that it can improve the ram air turbines performance by optimizing the blades shape near the hub region.