Abstract: With regard to uncertainties and difficult setting of the parameters in variable air volume(VAV) condition system,a new method of compound controller on fuzzy+variable universe fuzzy-PID based on genetic algorithm optimization is proposed.This controller is composed by fuzzy control and variable universe fuzzy-PID control.At the dynamic stage,the fuzzy control enables the system to have the most superior dynamic performance;at the steady-state stage,variable universe self-adaptive fuzzy-PID control enables the system to have the most superior steady-state performance.It applies genetic algorithm offline to optimizing the values of PID parameters of main controller.The output values of offline optimizing are the primary values of online adjusting.Adjusting the PID parameters online with the variable universe fuzzy inference,it ensures that the system has good self-adaptability.The fuzzy method of smooth switching guarantees the steady transition between the two different control strategies.The proposed compound control strategy is applied to the room temperature cascade control of VAV condition system.The simulation result shows that the system has good dynamic and steady-state performance,excellent anti-disturbance and robustness.