As a kind of semi-active controllable devices,Magneto-rheological(MR) damper has been increasingly widely used in various occasions of vibration suppression.However,the design of MR damper greatly depends on the engineering experience of designers,it is difficult to calculate the performances relatively accurate.With the Finite Element Method,the authors carry out the magnetic analysis on the given geometry of MR damper combined with the Couette flow analysis of MR damper,the dynamic curve of MR damper is obtained.The results show that the FEM magnetic analysis effectively predicts the yield shear force and flow shear force,it is coincident with the experimental data.It is validated that the methods described is suitable for the MR damper performance estimation of the same geometry,and is an effective means for the MR damper design with the given force.