Abstract: In order to enhance the sizing behavior of starch,a series of cynaoethyl starch with different degree of substitution were prepared by using acrylonitrile as etherifying agent and varying the feed ratio of acrylonitrile to cornstarch for changing the degree of substitution of the starch ether.The influences of the modification method and extent on the behavior of starch film and adhesion to fibers were studied.The experimental results demonstrate that the starch etherification can improve the breaking strength,breaking elongation,flex resistance and wear loss of starch film.As the degree of substitution increases,the adhesion of cynaoethyl starch to cotton fibers initially increases and then decreases.A maximal bonding strength can be achieved when the degree of substitution is 0.047.However,the adhesion of the modified starch to polyester and polyester/ cotton fibers decreases as the degree of substitution increases when the degree of substitution exceeds 0.017.