For the multi-motor winding system with parametric uncertainties and strong coupling, a decentralized optimal guaranteed cost control method is proposed. Firstly, a multi-motor winding system is regarded as a synthetic system with several dynamic interval subsystems. To describe the modifications of set point and the uncertain parameters, a interval matrix is introduced. Then, a decentralized optimal guaranteed cost controller is designed based on state feedback, and a sufficient condition for the existence of this controller is derived in terms of the linear matrix inequalities(LMIs). Finally, some simulation and experimental tests are conducted on a three-motor winding system. The experimental results show that the proposed decentralized optimal guaranteed cost controller can efficiently reduce control cost, strengthen the anti-jamming capability of the system, and ensure control precision of the tension and velocity.