Abstract: This paper deals with the reliable delay-dependent decentralized state-feedback guaranteed cost controller design problem for large-scale interconnected time-delay systems.Based on linear matrix inequality(LMI) approach,the existence conditions and parameterized representation of the reliable delay-dependent guaranteed cost controllers are developed.Furthermore,a convex optimization problem with LMI constraints is formulated to design the optimal guaranteed cost fault-tolerant controller.A simulation example shows the efficiency of the design method.