Abstract: Group velocities of the fundamental mode of Rayleigh waves are measured for the NS seimic belt,China and regions on its sides. Systematic differences are found between the wave paths. Shear wave velocity structures are obtained by inversing the dispersions. According to the velocity in the intermediate crust,the structures,can likely be classified into the reverse,low (non-reverse) and high velocity models. These can be tectonically related to the active,reactivated and stable regions respectively.