Abstract: Strong motion records of 64 Wenchuan Earthquake aftershocks are processed. Using the NGA model and 1D nonlinear site response analysis model, the attenuation relationships of ground motion for Wenchuan Earthquake region on various site classes are extracted from the records. The attenuation relationships are presented in terms of the peak ground accelerations, peak ground velocities and spectral accelerations for several periods. In comparison with other research results, it is shown that the predicted ground motions from NGA model are lower on rock sites but higher on soil sites.