Abstract: The paper analyzed principle of mechanical system of crawler travel system, and used multi-body dynamics software of RecurDyn to do simulation and analysis of walking state on flat road with soft soil of virtual prototype of compound obstacle crossing robot with master-slave track. The simulation results show that the gravity center of the prototype does not coincide with the geometric center, which leads down track of guide wheel to sink lower than other tracks, while the uneven pressure distribution may lead to locally grounding of track and reducing track life. So the rational allocation of gravity center of prototype should be paid attention to during design.