The structure function of residual wavefront phase perturbation compensated by an adaptive optics system has been derived by means of frozen turbulence hypothesis and geometric optics approach. According to the relationship between Strehl ratio of the system and the residual phase structure function, the analytical expression about the influence of spatial temporal transfer function, atmospheric turbulence, transverse wind speed along the light propagation path, angular velocity of the observed object and time delay of the system on the compensation effect of the system has been obtained.