Abstract: Based on the experimental modal analytical method to study structural dynamic characteristics of a radial gate, a design of structure optimization is put forward as for a flow-induced vibration problem from a super size radial gate of spillway for hydraulic projects. Passing by hydraulic and elastic model tests, the results show that the design making good dynamic characteristics for the radial gate has advantages for both impact loadings and the dynamic responses. Result of this research shows that the radial gate structure optimization improves its ability of vibration resistance. With good watertight seal, avoiding keeping 0.6―0.7 opening, standard operation etc., there will be no harmful vibration of radial gate.