Abstract: An immune PID-immune P cascade control strategy is presented for the water level control system of boiler drum in power station,which uses the regulating rules in feedback response process of biological immune systems.Immune P controller is used in the inner loop to quickly eliminate the disturbance of water-feed quantity,and immune PID controller is used in the outer loop to keep the water level at the set point and effectively overcome the disturbance of steam flux.The structure and algorithms of the strategy are very simple,enabling it to be easy to implement in engineering practice.Plenty of simulation tests show that this control strategy is superior to the traditional PID cascade control method.It can adapt variations of the object's parameters and has strong robustness,self-adapt-(ability) and anti-disturbance ability.