The ship wave caused by ships exiting from or entering the shiplock would enlarge the mooring force of berthed ships in the shiplock and be harmful for the mooring safety. Large-size ships entering or exiting from the shiplock may cause greater ship-induced waves and give remarkable influences upon the berthed ships. So to study the mooring force of the berthed ships caused by moving ships is necessary and important. The mooring force of the large-size ships in the Three Gorges shiplock is studied by conducting a physical model test of the shiplock, of which the scale is 1:36.3. A 5 000 t class ship model is used for the tests. The analysis results show that the ship speed gives a great influence on the mooring force. And if the water depth in the shiplock is 5.5 m, the slip speed exceeds 0.5 m/s, and the mooring force on typical berthed ship may exceed the standard value specified by the codes. When the water depth in the Three Gorges shiplock is 5.5 m, and the ship is berthed in the shiplock, the speed of other ships entering or exiting from the shiplock should be lower than 0.5 m/s for the safety.