Abstract: Take grape Muscat Hamburg as materials，using grapevine seedless agents（main components were GA3）dunking the fruit clusters made the seedlessness treatment during the blooming period，measured the polyphenols contents and the antioxidant capacity of grape fruit，leaves，young stems and tendril by colorimetric method and clearance free radical in vitro method during the whole growth period. The results showed that after the seedless treatment，phenols materials and antioxidation ability in berries decreased significantly，phenols materials and antioxidation ability in leaves and young stems somewhat increased，phenols materials in tendrils had little difference compared to control，antioxidation ability was slightly higher than control；Changes regularity of clearing the free radicle were opposite to leaves，young stems and tendrils organs，antioxidation ability of control fruits was stronger than that of seedlessness treatment.

Key words: grapevine, seedlessness, phenolics, antioxidant capacity