This paper deals with the processing principle of the tension control system, the constructing of mathematical models, and the implementing of control measures,while fibre bobbins open rolling and close rolling in the process of preparation of preimpregnated materials. These are all practiced and verified in the equipment for preparing preimpregnated materials, and it shows good results.During the process of fibre pick up, the new product “ratio electromagnet-mechanically restraining device (REMRD)” adjusts and controls the reel tension, so plays a critical role in keeping the fibre roving tension constant. The basic theory of REMRD is described in the article. In the course of prepreg take-up, the tri-roller-swinging arm-compensator is used, companied by linear velocity follower control and rolling-up-transmission compensator control, to attain prepreg draw-off roller’s and take-up roller’s immediate following ability and tension stability.