Large –scale aluminum ring rolling mill is the core of ring rolling ,it is required for automatic control system to realize high precision and fast response.Based on the configuration of the equipment, characteristics of ring rolling and the process flow of production, the paper not only studied the Control principle of the automatic control system but also designed the control scheme of software and hardware. The core of system is PLC. The system can effectively control hydraulic system, measurement system, feeding servo system by the cooperation of PLC and human machine interface (HMI). It realized fully automatic operation under the ring rolling mill close-loop control. The high precision control and safe operation can be realized by using multi network communication technology and advanced full AC drive system .The rolling quality of rings is high. The design accords with the control logic requirements of rolling process control. The control system is smooth and reliable.