Hydraulic tensioning steel halter is planned to be equipped for the opening and closing of the slide plane gate at the bottom outlet of Xiangjiaba dam. It is the first to install this equipment in hydropower projects. The flow-induced vibration of the gate is highly concerned as the large-sized gate opens and closes at the speed of 5m /h with high water head. Hydroelastic 1 ∶ 30 model and numerical model are employed to obtain the dynamic properties, the static and dynamic stresses of the gate structure, the fluctuating pressure on the gate and the vibration characteristics, all of which are verified by tests and calculations. The study finds no resonance during the closing and opening of the gate, which thus is dynamically safe with small vibration. In addition, it is suggested to set up aeration facilities at the entrance of the bottom outlet to release the negative pressure on the back of gate and add extra weight to the gate to enable it closing easily.