Abstract: Guigang Second Line Ship Lock is an important navigation hub in the main shipping line of the Xijiang River. It adopts a simple decentralized filling and emptying system with a layout of gate wall gallery side branch outlet and double open ditch energy dissipation, which is rare in China. In order to verify the reasonable layout of the system and the proper operation mode of the gate valve, and to ensure the safe and efficient operation of the ship lock, the prototype observation test of the hydraulic characteristics of the filling and emptying system was carried out. The observation results show that the hydraulic characteristics of the lock chamber and the berthing conditions of the ship can basically meet the code and design requirements, and the flow patterns at the inlet and outlet of the lock and in the lock chamber are good; and under the current ship lock head and recommended gate valve operation mode, the superelevation and drop in the lock chamber at the end of water conveyance exceed the specification requirements. After putting forward improvement measures for the operation mode of the lock valve, the problem has been improved. There is a deviation in the discharge coefficient between the prototype and the model of the ship lock, and the deviation value does not exceed 6%. The operation of the double-track lock under different working sequences has little influence on each other.