Abstract: It is difficult to size polyester yarns with starch. This paper studied the changes of morphological structure and chemical compositions of polyester fibers by corona discharge treatment and the sizing property of polyester yarns when using different proportions of PVA/starch. The corona discharge treatment conditions were varied as a function of volatage and duration of treatment, and the influence of the sizes with different proportions of PVA/starch on the sizing property of the treated polyester yarns. The resuots indicated that affter sizing the abrasion resistance of corona discharge treated polyester yarns is enhanced, the hairiness reduced, and the comprehensive properties significantly improved. It′s possible to size polyester yarns with little or no PVA in the sizing agent.