In order to avoid the film defect caused by tension in the process of winding magnetron sputtering coating as well as the slow response and poor stability of original tension system, the tension system was analyzed and optimized. It was determined through analysis that the key factors influencing tension are the speed of winding and unwinding as well as the change of the roller's diameter. The dynamics model of tension system was established and Simulink was used for simulation analysis of the tension control system. Al2 O3 films were prepared in original equipment and transformed equipment respectively for experimental verification. The SEM images of Al2 O3 prepared in different ways of tension control were compared. The result showed that the reconstructed system can realize real-time adjustment of the film tension in 0. 65 s, but the original system need 8 s; the reconstructed system can ensure constant tension, compact and uniform film layer, and no wrinkle and gap between the film layers.