A self-lifting obstacle crossing guide robot is designed. The robot could quickly and safely walk on flat roads，make a sound of the speech information when encounter obstacles，and cross the lower obstacle shoulder of a road. The robot was used of a new obstacle crossing mechanism with smooth movement. The working principle of the obstacle crossing mechanism was introduced，the model of obstacle crossing mechanism was built，the dynamic analysis using the Lagrange equation was completed, and the appropriate power components were selected. Through experimental verification，the robot can easily realize the obstacle crossing function with smooth movement.