Abstract: In order to reduce the cost of desilting, and improve the efficiency of navigation, the desilting in the downstream approach channel by ship lock sluicing is studied with engineering practice. A two-dimensional numerical water-sediment model has been established for simulated analysis, and the hydraulic test of flow field and sediment field has been employed for verification. It explores the rules of sediment deposition in the entrance of approaching channel, analyzes the hydraulic characteristics of water conveyance system in ship lock, studies the scouring effect in the different scouring discharge, scouring time and initial siltation thickness, and obtains the relationship between water discharge of ship lock and the maximum siltation thickness. The results show that the maximum siltation thickness is decreasing with the increasing scouring time linearly under the same initial terrain and discharge, and the slop of sediment thickness is increasing with the scouring discharge. When the thickness decreases to a critical value, the scouring effect becomes weakened with the increasing scouring speed. Research results may provide theoretical reference for the desalting technology of the channel by the use of lock emptying.