A physical model on Jiaogang ship lock is set up, and the force of sluice gate hoist is studied by the model. The results show that the upper and down sluice gate can be opened in the same time in the following conditions: 1) The original tide range is less than 0.39 m when upstream water stage is 3.71 m; 2) The original tide range is from -0.34 m to 0.38 m when the upstream water stage is 1.64 m; 3) The original tide range is from -0.37 m to 0.43 m when the upstream water stage is 0.96 m. The force variation law of sluice gate hoist provides reference for the similar study.