Compared with miter gate,the single leaf gate can commendably adapt to the “narrow high type” ship locks on the river in Western China,but the study on the hydrodynamic characteristics of the large single leaf gate is almost blank.In order to explore the change characteristics of hydrodynamic resisting torque in large single leaf gate operation,we carry out a series of basic research on submergence which is the main factor.Through associated physical model test of the single leaf gate and the hydraulic hoist with the scale 1:20,the change characteristics of the hydrodynamic resisting torque during the opening and closing process are analyzed and the relationship between the maximum torque and the submergence and the angular acceleration is obtained.The results show that the greater the submergence is,the more sensitive the maximum torque to the change of the angular acceleration will be.The single leaf gate should adopt the stepless change speed under the large submergence condition to decrease the initial and final angular acceleration,which can reduce the maximum torque and the hydraulic hoist design difficulties.