To solve the problems of plunger valve cavitation and vibration of hydraulic ship lift,with a model scaled 1:10.667 physical,the flow coefficient,cavitation morphology,critical cavitation number of the high water head plunger valve are researched.For alleviating cavitation,air entrainment measures are put forward.The valve decompression model test verifies that:the valve segment cavitation is basically eliminated and vibration is declined obviously when each valve is entrained air with a mount of 0.1 m3/s .The effect of air entrainment measures to alleviate cavitation is significant.