Abstract: Flow-induced rudder system vibration has a great influence on the stealthiness of underwater vehicles. In order to study the vibration characteristics of rudder systems, a mathematical model of a binary linear flutter rudder system is built according to a simplified rudder system structure. Next, the conditions of low speed flutter of the rudder system are determined, and the main influence factors and control rules of the low speed flutter are obtained. In addition, flow-induced vibration tests of the rudder model are made in a gravitation water tunnel, and a study is made of the influences on the rudder system caused by variations in such main parameters as support stiffness, torsional stiffness, mass center position and stiffness center position. The results show that the structural design has a great influence on flow-induced rudder system vi-bration. The flow-induced vibration of the rudder system can be effectively suppressed through the match-ing design of such parameters as the frequency ratio of heave motion and torsion motion, the ratio of the structural mass and added mass, and the positions of the stiffness center, mass center and chord center.