In order to reasonably set the rigid layer depth in pavement structure and improve the rationality of backcalculated modulus, the fullscale test track was used to measure the layerbylayer deflection basins at each structural layer of pavement using falling weight deflectometer(FWD), the influences of rigid layer depth and stress level on the layerbylayer backcalculation modulus of subgrade were analyzed, and a setting method for the rigid layer depth based on the consistency of subgrade modulus was developed. The results of the case study show that, compared with the stress level, the effect of the rigid layer depth on the subgrade backcalculated modulus is significant. The relationship between the setting depth of the rigid layer and the pavement equivalent thickness is exponential. The comparison with other setting method of rigid layer depth show that the method developed in this paper can significantly improve the consistency of the layerbylayer backcalculated modulus of subgrade and drastically reduce the coefficient of variation from more than 13% to 6.9%.