Magneto-rheological fluids (or simply “MR” fluids) belong to the class of controllable fluids. The merit of MR fluids is their ability to reversibly change from free-flowing, having a controllable yield strength in milliseconds when exposed to a magnetic field. Furthermore, MR fluids provide simple, quiet, rapid response interfaces between electronic controls and mechanical systems. In the paper, a performance evaluation of 6x6 military vehicle with MR damper is investigated. The sky hook as a algorithm to control the damping force is designed. Through mobility test of 6x6 military vehicle, the performances of passive suspension and the semi-active suspension with MR damper are compared.