The high resolution numerical simulation of rotor/wingbody interaction flowfield in hover is crucial for the accurate prediction of aerodynamic performance of the tiltrotor aircraft. The study of interaction flowfield high resolution numerical simulation is the important issues of helicopter aerodynamics. Based on the moving-embedded grid technique, a CFD simulation method for predicting unsteady flowfield is established. Reynolds-averaged Navier-Stokes(RANS) equations are used as governing equations and Spalart-Allmaras turbulence model is employed, implicit LU-SGS scheme is adopted. On this basis, the unsteady interaction flowfield of the rotor/wingbody are investigated in deep research, and the special phenomenon 'fountain effect' is simulated, the results indicate that the total thrust loss is about 16.6% as compared to the isolated rotor. Furthermore, it studies the different preset flaps/ailerons affect on decreasing rotor/wingbody aerodynamic interference. The results show that the lowest aerodynamic interference presents the preset flaps/ailerons angle 45 degree. In the preset angle of 45 degree, the total thrust loss reduces to 13.8% from 16.6%.