The problem of disturbances attenuation for interconnected system using decentralized controls, such that the effect of the disturbances on the whole system is reduced to an acceptable level is considered. The design procedure involves constructing H-infinity local state feedback controls via Riccati equation approach. Then the relationship between the H-infinity control theory and the required decentralized controllers is established. Complete solutions to this problem are carried out merely by iteratively solving a set of local algebraic Riccati equations.