Based on the analysis of the reciprocities among the toll rate, traffic volume and charge volume, and their features as well, the basic ideas and methods of the toll rate determination for ring expressway are put forward. The paper establishes the function of general traffic impedance which includes the tolls parameter under the preconditions of the highway planning and its forecast traffic volumes of Chongqing. By the use of the TRANSCAD, which is a traffic planning software, the traffic volumes on the ring expressway are assigned successfully helped by SUE model. Finally, the paper gives the optimal toll rate for the ring expressway of Chongqing.