VAV air-conditioning system has the characters of nonlinear and non-stationary under the influence of many factors, so it is hard to tune the parameters of the fuzzy control system. According to the structure and operation principle of VAV air-conditioning system, the monitoring system has been developed. The conventional fuzzy control algorithm, temperature self-tuning parameters fuzzy control algorithm and variable universe adaptive fuzzy control algorithm were researched in the system. The relationship between the scale factors and several main performance indexes of the system's respond curve like overshoot, steady-state error and transient time has been analyzed. The experiments results indicate that the variable universe fuzzy control algorithm can improve the performance of the fuzzy controlle, the combination property index decreases over 17%. The algorithm is feasible to use it on line since it is simple and need few system resources.