Abstract: With the increasing height of hydraulic ship lifts, the water level synchronization issue among the vertical shafts becomes more prominent and is a key technical challenge for the safe operation of the ship lifts. It is necessary to conduct research on this topic. Based on the design concept of "longitudinal corridor water supply system + overall connectivity of vertical shafts" hydraulic drive system, this paper establishes a 1∶30 generalized physical model of hydraulic ship lifts and investigates the basic laws of water level variation in the vertical shafts of this new hydraulic drive system under non-steady flow conditions. The influence of two key factors, namely the initial water depth and water flow rate, on the water level synchronization of the vertical shafts is analyzed. Experimental results show that during the initial filling stage, a longitudinal slope is formed in the vertically connected shafts, which undergoes oscillation and attenuation. After the participation of balance weights, rectification effect is achieved, which helps to reduce the slope of the water surface in the vertical shafts and significantly shorten the oscillation attenuation time. The water level synchronization of the vertical shafts is high throughout the water supply process, and the forces on the balance weights are uniform. Under the condition of initial water depth greater than 15 m, the new hydraulic drive system can meet the water level synchronization requirements of hydraulic ship lifts with a lifting height of hundreds of meters.