The new tuning rules of the PID controller for the rejection of load disturbance are proposed incorporating with real-coded genetic algorithms (RCGAs). The optimal gain parameters of the PID controller for a first-order plus time delay model are obtained based on a RCGA. Then tuning formula are derived using the tuned parameters sets potential tuning rule models and another RCGA. The performance criteria of the controller are adopted as ISE, IAE and ITAE. A series of simulation are carried out to verify the effectiveness of the proposed tuning rules.