Chaos and chaos control received extensive attention. The fuzzy controller is used to control chaotic systems in this paper. The accuracy of fuzzy controller is not high and there is contradiction between the number of control rules and accuracy. Accordingly a variable universe fuzzy controller based on ant colony optimization algorithm is proposed. By analyzing the two kinds of contraction-expansion factors, one of them was found unable to satisfy the general contraction-expansion factor condition. A method for optimizing the contraction-expansion factors intelligently via ant colony optimization algorithm is proposed. A variable universe fuzzy controller based on ant colony optimization algorithm is constituted and used to control the Duffing chaotic system. Simulation results show that the control method is superior to the others both in convergence speed and steady-state performance.