Abstract: In this paper, we present sufficient conditions for existence of decentralized robust controller and tracking controller for large-scale uncertain systems. The uncertainty is value bounded and can be dissatisfied with so-called matching conditions. With this representation, we give robust decentralized control laws for two classes of uncertain interconnected systems. In the former, the uncertainties may be time-varying, and the controlled system can converge exponentially with a prescribed rate under the decentralized robust controller. In the latter, the uncertainties are time-invariant, and we give a robust tracking controller which guarantees the controlled system to approach the reference input exponentially.