In this paper, a novel fuzzy ant colony system (FACS) with a fuzzy mechanism and a fuzzy probable mechanism is presented for parameter determinations. Based on the fuzzy rules, the transition behavior of ants is simulated. The fuzzy probable mechanism is introduced with fuzzy probable rules to implement the diverse searching. The fuzzy probable rules are proposed to have the fuzziness in the antecedent parts and the probability in the consequent parts. To indicate the effectiveness, the fuzzy ant colony system is applied to find the proper parameters of the fuzzy sliding controllers for swinging and balancing the inverted pendulum and cart system. Also, the comparisons between the proposed fuzzy ant colony system and other ant colony optimization algorithms are provided in the simulations.