Abstract: The hydrodynamic characteristics of the emptying valve of the Three Gorges Lock's last chamber during emergent closing operation are described. Based on the results of physical model tests and mathematical model calculations, the characteristics of the flow pattern alternating between non-pressure flow and pressure flow, and the influence of valve closing's rate and initial valve closing opening on the impulsive characteristics of the culvert behind the valve are analyzed. The maximum water head, valve hoisting loads, valve axle loads and cavitation characteristics of the valve stretch are measured and studied.