A method for the design of linear constant decentralized robust controllers for a class of uncertain interconnected systems is presented in this paper. The uncertainties are assumed to satisfy the general matching conditions for each decomposed subsystem, and both stabilizing control and output tracking control are considered here, In the former, the uncertainties may be time-varying, and the system can be exponentially stabilized, In the latter, with the assumption of time-invariant uncertainties, the system can approach the constant reference input and reject constant disturbances with a prescribed convergence rate,