A novel 8U (universal joint) parallel mechanism, being able to do omnidirectional rolling motion is proposed in this paper. This mobile mechanism owns the priority of simple structure and rolling easily on terrains with loose soil, dirt or sand with only a few actuations. Its spatial closed compact structure is described firstly. In addition, the omnidirectional locomotion accompanied with DOF (degree of freedom) alternation between one and two is revealed by mobility analysis. After that, the feasibility of rolling motion is verified theoretically by stability analysis. Finally, the omnidirectinoal rolling motion is testified both by virtual and prototype experiments.