A check gate was taken as an example to study the dynamic characteristics of a large width-height ratio steel radial gate under the action of water pulsation, by means of establishing the finite element model to analyze the effects of fluid-solid coupling and arm thickness on the gate vibration characteristics. Based on the random vibration method, the fluid-induced vibration displacement and stress response of the gate under the action of pulsating flow were obtained. The dynamic response of the gate was evaluated by the dynamic coefficient method. The results show that the basic order vibration of the gate is less affected by water, and the lower order vibration is more affected by the arm. The maximum displacement response of the flow-induced vibration under typical working conditions of the gate is 4. 029 mm, and the maximum dynamic stress is 61. 247 MPa. The dynamic coefficients are all lower than 1. 20. The overall dynamic stress level is low, and the gate can operate safely under the action of dynamic water.