Cotton and polyester/cotton blend yarns were sized with different size formulation of varying starch to PVA ratio and tested for breaking strength, elongation, lea strength hairiness, and abrasion resistance which are closely relative to the efficiency of weaving. The viscosity of sizing solution was influenced by the types of modification of cone starch and the mixing ratio of starch to PVA. The viscosity was also varied with the concentration of adhesive. The size add-on was determined by the viscosity of size and the pressure of squeezing roller of the slasher. The lea strength was significant by influence with types of starch applied. The physical properties of film casted from the size solution were tested and the results showed that the properties were affected by the concentration of size and the types of starch used. For the constant mixing ratio of starch to PVA, the hairiness measurement of sized cotton yarn by F-index tester for the intervals of length(1-2mm, 2-3mm, above 3mm) showed that the hairiness was decreased by increasing of the pressure of the squeezing in roller and with the viscosity of size up to the optimum pressure, but the hairiness was increased with the pressure and the viscosity of size above the optimum pressure.