Abstract: A shaftless-leakage protection viscous damper was presented，its basic principle was that the deformation of oil cavity itself drove viscous flow through damping hole back and forth so that energy dissipated． Through performance test and finite element analysis，the feasibility of the damper structure schemes was preliminary verified． The results of the type of damping vibration reduction performance based on Benchmark model of structural vibration control showed that the shaftless-leakage protection viscous damper has a good damping effect．