Aiming at the problems existing in the bolt drilling rig, an intelligent visualization scheme based on PLC, interface and frequency converter was used to reform the control system of a certain type of bolt rig. Through analyzing the control principle of the system, the PLC terminal wiring diagram was designed, the flow chart of the control system was given, and finally the PLC program and the manmachine interface design were finished. The experimental results show that the modified control system has the advantages of simple circuit, good reliability, high efficiency and easy maintenance.