Abstract: A new reconfigurable robot is introduced,which can give output in different forms under various constraint conditions from one driving torque.It thus can cross over obstacles autonomously.Because the oriented wheel and the arm have fatal influence on the height of the crossing obstacle,a new motion planning method for robot to cross over obstacles is proposed by using environment and attitude of the arm,and the height of the crossing obstacles will greatly be improved.The validity of the planning is proven by experiments on a prototype.