To investigate the change rule of multiphase flow characteristics in the turning motion of supercavitation vehicle, the RANS equation is solved based on the finite volume method and VOF multiphase flow model. Combined with the dynamic mesh technology, an unsteady numerical simulation study is conducted. By comparing the numerical simulation results with the calculation results based on Logvinovich independence principle, the effectiveness of the numerical simulation method is validated. The influence of rotate center of vehicle on the cavity shape and that of turning radiuses on the hydrodynamic characteristics of vehicle for the turning motion are analyzed by the numerical simulation. The results show that the numerical simulation method of dynamic mesh can simulate the cavitary shape of the turning motion of the supercavitation vehicle better. The rotation center of the vehicle has an important influence on the wetting area on the inner or outer surface of the turning radius of the vehicle. The valley environment of the vehicle makes the shape of the super cavity tail appear inclined double vortex tubes under the combined action of gravity and inertial force. During the turning motion, when the wetting area appears on the surface of the vehicle, the fluid dynamics of the vehicle will have a small amplitude fluctuation. The fluid dynamics tends to be stable with the wetting area increasing. And the trajectory radius of the turning motion has a great influence on the fluid dynamics of the vehicle. The smaller the turning radius is, the greater the influence is.