Abstract: Crustal thickness H and v_P/v_S ratio are two basic parameters for deciphering the crustal structure. We present an improved technique to constrain crustal thickness, v_P/v_S ratio and average P-wave velocity by using receiver function, surface wave dispersion and gravity data. Synthetic tests show that the improved method not only can accurately estimate H and v_P/v_S ratio, but also can give a reliable determination of the average crustal v_P. Field data from two stations of South China are analyzed by the improved method, and the results also show the feasibility of the new method in constraining crustal properties.