Abstract: The water entry cavity experiment of a vehicle with a disc cavitator is carried out under the condition of the vehicle's posture is constrained. The underwater flow characteristics of water entry partial cavity, water entry cavity that the cavity is just closing on the body tail, water entry supercavitation, and inclined water entry cavity, were researched. The relationship between cavity sizes and the Froude number and Euler number were analyzed, the cavity length variation were developed, and the flow mechanism obtained in experiment were discussed. The results show that water entry partial cavity becomes longer after deep water closure, and that the cavity is collapsing with cloud cavity. When the cavity is closed at the end of the vehicle tail, the reentrant jet is easily formed and interacts with body tail and cavity which influence the flow characteristics of the cavity tail. The water entry supercavitation has good stability. The inclined water entry cavity is affected by gravity, and the cavity tail is floating upwards, resulting in a cavity tail snap by the interaction of the cavity and the body tail. The gas elastic effect is more obvious in the inclined water entry cavity, the waveform of cavity wall appears, and the cavity length oscillates.