Fuzzy direct adaptive sliding mode controller is designed to realize the decentralized control for a class of nonlinear interconnected large-scale systems with unknown functions. It uses the methods of fuzzy adaptive control, fuzzy logic approximation and fuzzy sliding mode control to approximate the ideal controller. Through the adaptive process of a parameter, the affection of interconnected terms on the subsystems is counteracted. The fuzzy sliding mode control is introduced to attenuate the fuzzy approximation errors. Simultaneity, the close-loop system is stable in Lyapunov sense and the tracking error converges to a neighbourhood of zero.