A　dynamic　model　of　the　extreme　states　of　all-wheel-drive　robot　climbing　over　obstacles　is　established　according　to　its　basic　structure.　The　torque　distribution　between　different　driving　wheels　and　the　influential　factors　of　gravity　allocation　are　included　in　the　model.　Based　on　this　model,　the　minimum　driving　capability　and　the　gravity　allocation　condition　can　be　determined　to　meet　the　climbing　requirements　of　the　all-wheel-drive　robot.