Based on the configurations of the track type travel mechanism, instead of wheels, the tracks were introduced into the rocker-type robot mobile system, and various configurations of the rocker-type track suspensions were obtained. Through analyzing characteristics of the suspensions, a rocker-type unsymmetrical W-shaped track mobile system was presented. The rear main tracks of the W-shaped tracks were longer than the front ones. The prototype’s obstacles-surmounting capabilities including ditch-crossing, step and stairs-climbing were analyzed. The prototype could climb up a 320mm-high step, climb down a 520mm-high step, cross a 490mm-wide ditch. The capabilities analysis and prototype test results indicated that the rocker-type unsymmetrical W-shaped track mobile platform had excellent passive adaptability to rugged unstructured terrain environments and strong obstacles-surmounting capabilities.