A new transient aerodynamics model is founded based on time- stepping free-wake and ground panel models for rotor performance prediction in a xial flying condition in ground effect. A 3rd-order CB3D scheme is used to impr o ve the calculation stability and efficiency of wake geometry. The prediction rev eals that CB3D scheme can inhibit the numerical errors caused by ground effectiv ely and get a more truthful wake geometry. A ″constant volume rectification″ m ethod is also incorporated into the model to rectify the wake vortices falling b elo w the ground unphysically in transient state. The predicted result of the new mo del is compared with experimental data to validate its accuracy. Then the aerody namics characteristics of rotor in axial flying near flat or inclined ground are analyzed．