Abstract: By combining the experimental studies carried out in a closed-loop cavitation tunnel and the numerical investigation of flow-induced vibration, the flow-induced vibration characteristics of a flexible hydrofoil in unsteady cavitation are investigated. A high-speed video camera is used to visualize the unsteady cavitating flow patterns, and a laser doppler is used to measure the flow-induced vibration characteristics of the flexible hydrofoil. A multi-field synchronous measuring system is used to measure the cavity shape and hydrofoil vibration. Based on the results of the experiment, further numerical study is performed. The results show that:the process of the flow-induced vibration characteristics is a quasi-periodic variation, and one cycle can be divided into three stages which are attached cavity development, cavity fluctuation and cavity shedding. The flow-induced vibration is mainly influenced by the development of the cavitation, and the main frequency is corresponding to the cavity shedding frequency. During the different process of the cavitation development, it shows the different variation characteristics, and the variation is fiercer during the stages of cavity fluctuation and cavity shedding.