Aiming at the 2009 Asia-Pacific Robot Competition, the discussion was extended of how to make the carrying pole keeping balance and how to adjusting the height of the carrying pole while the automatic and manual robots go through the ramp up and down. How to adjust height by back and front robots during elevating sedan chair was analyzed, and an elevating system of robot was introduced. According to the characteristics and routes of uphill and downhill of robots, the method of using separately serial port position control and stepping control was adopted for lifting machine by motor, so as to maintain the sedan chair keeping balance. After testing beyond the experimental field, the results show that the robot can work coordinately, and realize keeping balance while up and down the ramp.