The lowest chamber of the lock of TGP is linked with the main channel of Yangtze River by 1 350 m long tunnel. The flow - induced vibrations of emptying valve were studied by a hydroelastic model. The frequencies and modal shapes of the valve were obtained by both experimental and analytical modal analysis methods. The normal and emergency operating situation were simulated in model tests. The tests results show as follows: With 2 minutes opening or closing time,i.e., normal operating condition, the mean square root(MSR) value of vibration acceleration usually is less than 5.0 cm/s2, only at small opening (0.0-0.1) it reaches 25.37 cm/s2. In emergency condition during two valves closing simultanously in 4 minutes from full opening condition, the MSR value of vibration acceleration reaches 22.57 cm/s2, but when single valve closing in the same way the vibration acceleration of the valve is 2 times that appeared during two valves closing. The faster the valve closing speed,the stronger the vibrations are. With opening valve in normal speed till its halfway then immediately closing in 4 minutes, the vibrations are even stronger than those appeared during closing from full open condition. Because of low closing speed designed and the effect on pressure regulation of the overhaul shaft, harmful water hammer phenomena doesnt take place during tests. The vibration of the valve compared with that sustained by similar valve in other project is not
harmful to its safety. 