An active adaptive fuzzy integral sliding mode controller is proposed for a unified chaotic system with parametric uncertainties under external perturbation. An improved control method is designed to guarantee the stability, while maintaining the transient performances of the original nonlinear integral sliding mode control. The proposed method reduces the effects of both the uncontrollable state of unified chaotic system and approximation error of adaptive fuzzy compensator on system state error. The stability of the controller is analyzed by Lyapunov stability theorem. The simulation results show that the system states can be controlled to target points with parametric uncertainties under external perturbation. The effectiveness of this method is illustrated by the numerical simulation.