In this paper, we investigate the decentralized control problem for largescale interconnected systems. The synthesis of the decentralized controller consists in determining gains which ensure the stability of the global system. To calculate these gains, three approaches are presented. Our main contribution is to develop a new decentralized stabilization approach which the decentralized local gains are calculated and formulated via the resolution of linear matrix inequalities (LMIs) problem. A numerical simulation comparison of the three methods is performed on an interconnected double-parallel inverted pendulum.