Abstract: To meet the requirements of glass-wall cleaning for high-rise buildings, a pneumatically actuated climbing robot has been developed. However, the characteristics of low-stiffness and nonlinearity in pneumatic system make accuratecylinder position control difficulty. To solve this problem, a new bang-bang control method was proposed. The whole control process is segmented into several bang-bang periods according to the piston position and velocity of cylinder. Withthis method, when the piston of cylinder is far from set position it can move quickly towards the target, and when the piston is near the set point it will reach the target accurately. Testing results show that this control method can effectively improve the control quality.