With the elastic bearing, the model of elastic bending beam was firstly used to simulate the cable and deck of cable-stayed bridge. The dynamic governing equations of beam of multi-cables and one girder composite structure were derived by Hamilton’s principle and the free vibration equations of beam with consideration of axial force. In addition, the program for solving the dynamic governing equations was established by transfer matrix method,and the parameters including the number of cable, the axial force and damage of beam were considered in the theoretical investigation. The analysis results indicate that the stiffness of beam descends with the increasing of the length and the axial force of beam on the construction. On the contrary, the axial force is useful for rejecting stiffness decending due to the crack. Therefore, the effects of the force of cable on dynamic behaviors of the deck should be taken into auount on the erection of bridge.