The expansion and reconstruction project of the Yuxi first-line ship lock increased the width of the sector gate to 34 m for the first time. To improve the operation efficiency of the ship lock and give full play to the advantages of the opening and closing of the dynamic water of the sector gate,an experimental study on the water conveyance condition of the large sector gate joint is carried out. Based on the hydrodynamic characteristics of the sector gate and the safety of ship berthing,the study puts forward the operating conditions of the large triangular gate of the Yuxi new ship lock. The conditions are as follows:1）The water conveyance of the sector gate should be opened within 1 m head difference as far as possible. 2）The opening degree of the gate should be controlled within 1 m. 3）With the decrease of the head difference,the opening degree of the gate can be further increased.