The electric control system is the core of operation control for a rig, its high security and reliability are the important guarantee for the normal operation. A scheme of control system based on CAN bus technology is proposed in this paper, the system structure and function design are discussed. Through its application on SDC2500 vehicle-mounted hydraulic, it is proved that this control system based on CAN bus technology has advantages of simple wiring, remote integrated control, fault early warning and improved drilling rig safety.