Abstract: A high efficient oil film damper,namely Movable outer Ring Squeeze Film Damper (MRSFD) is developed to meet the demands of modern gas turbine engines and other high speed rotating machinery on vibration control.By adding a flexible support outside,the outer ring of conventional Squeeze Film Damper (SFD) could be pushed under high oil forces caused by the squeezing motion of the journal.The vibration controllabilities of MRSFD and SFD are investigated and compared both theoretically and experimentally.It is proved that the nonlinear vibration characteristics such as jump phenomenon of SFD systems could be avoided under much greater unbalance level with MRSFD systems.As a novel oil film damper,MRSFD provides more effective vibration control for rotor systems and improves the unbalance loading ability of the damped supports.