Abstract: The dynamic characteristics of lunar rover are very complex when the rover steers on soft soil. The paper analyzes dynamics modeling of lunar rover steers on soft soil based on the known work. A kinematic expression of 4 wheel steering for 6 wheel lunar rovers is presented, a dynamic model of 4 wheel steering for rovers driving on soft soil is expounded, and some simplified methods are presented. At last, the steady characteristics is analyzed. The results provide a foundation for designing of steering system of rovers.