Intelligent PID controller is a combination of conventional PID controller and intelligent control technology. Fuzzy control, neural networks and genetic algorithm with conventional PID controller have been summarized as the primary research findings in recent years in this paper. The application and studies of intelligent PID controller in power plant major thermal process control system have been reviewed as well. Theoretical study and practical application indicate that the application of intelligent PID controller in power plant thermal process control is practicable and effective and has large space to be improved and developed. The paper has presented the study direction of intelligent PID controller and questions remained to be solved, meanwhile, it also put forward some suggestions for the application of intelligent PID controller in power plant thermal process control.