Aiming at the prestressing problem and vibration problem of the miter gate of the lower head of Dayuandu second-line ship lock,we carry out the three-dimensional finite element static and dynamic calculations,give multiple sets of solutions of the optimized model,and obtain the optimal prestress of the back tie rod and the value of the natural vibration frequency of the gate.The analysis results show that the structural stress is less than the allowable value of the material.The lateral and vertical deformations of the lower corner of the door body’s slanted column and the lateral deformation of the midpoint of the door shaft column meet the requirements.A technical support is provided for the prestressed construction of the back tie rod and the frequent vibration of the miter gate during operation.