Abstract: A mechanical multi-rollers system was used to spread large tow carbon fibers, the force condition of large tow carbon fibers on different shaped rollers and the possible movement of fibers were analyzed, and the damage level and the dist ribution of spreaded fibers spreaded by different shaped rollers were studied also. Af ter amulti-rollers system within several equal diameter special-shaped rollers as kernel parts was determined , what kind of roles those factors such as the curvature of the special-shaped rollers and the tension play in spreading large tow carbon fibers were studied. It is determined that the optimal curvature radius of the special-shaped rollers and optimal tension exerted on fibers are 330 mm and 46. 6 N respectively.