Abstract: In order to ensure that the main tower is in the safe state during lifting of stiffening girders of suspension bridge,it is essential to determine the pushing values and pushing stages. A formula for the maximum allowable displacement of main tower was derived with Rayleigh-Ritz method based on energy principle. The pushing method of the main cable saddle was optimized from the perspective of both displacement of main tower top and stress at tower bottom. Finally,accuracy of the proposed formula was verified by the finite element method( FEM). The results show that the error between the result from proposed formula and that from FEM is 3. 4%,and the error from processes considering and without considering the effects of P-Δ on the main tower is 4. 6%. The maximum allowable displacement of the tower keeps increasing with the lifting of stiffening girders,and the increase amplitude can reach 19. 9%.Meanwhile,the pushing values and time interval should be gradually increased and pushing times should be reduced,which resolves the problem of saddle pushing of suspension bridge and optimizes stress state of the main tower.