Abstract: The basic concept of size compatibility a nd the adhesion role of sizes to fibers in warp yarns are introduced.In accordan ce with the damage manner of adhesion joint, the influences of morphological stru c ture of the adhesion layer formed among fibers in sized warp yarns upon the mech anical properties of sizes blends are discussed.The correlation be tween the compatibility and adhesive capacity of sizes is surveyed .It is concluded that the size blends will not show good adhesive capactiy when the compatibility of size components is too low.On the contrary,improvement on the compatibility of warp s izes certainly favors the adhesive capacity.