MR damper is analyzed on its mechanical characteristic, and is applied in multi-dimension damping in this paper.  A kind of three-translation parallel mechanism is used as main mechanism of multi-dim damping,  whose position and dynamics formula are deduced.  The input signal of controller is from the result of equation of kinematics,  and LQR is used as the semi-active control arithmetic.  Considering complexity of the dynamics equation in dynamic process,  a way is used in control progress when the mechanism is in a steady state through which the entire flat roof is limited adjacent to an equilibrium position.  The result of emulation confirms that the controller is effective.