Abstract: The speed proportions between lickerin and feed roller, cylinder and licherin, cylinder and doffer cause damage to fibers in carding process, which further influence yarn strength. The correlation degrees between yarn strength and the speed proportions were researched by grey relational analysis, and GM(0,N) prediction modal of yarn strength was also established. In result, the speed proportions were factors affecting yarn strength. Average relative error of GM(0,3) prediction modal was 1.57% and the modal was effective through error correction.