Abstract: Grape seeds have abundant polyphenols,such as flavonoids,especially proanthocyanidins,which show strong antioxidant activities and resistant abilities to many diseases. In this essay,Chardonnay grape seeds were grinded to ultrafine powder,and their antioxidant activities were tested. Meanwhile,ultrafine grape seed powder( UGSP) was added to cake at different concentrations( 5%,10%,and 15%),and a proper bakery process was established.At last,sensory evaluation and antioxidant effect of fortified cake were conducted to confirm the final amount of UGSP addition. The results showed that UGSP of Chardonnay had the ability to clear ABTS+· and showed Fe3 +reducing power( 12.83,10.80 mmol TE / g defatted dry weight,respectively). The fortified cake also showed strong antioxidant ability,the ABTS+·scavenging ability and Fe3 +reducing power of UGSP- fortified cake were enhanced significantly( p < 0.05) with the increasing amount of UGSP addition. What's more,the acid value and peroxide value of cake were inhibited by the addition of certain amount of UGSP during their shelf life. As to general sensory acceptance,cakes of different UGSP concentrations did not show significant difference. Thus,combining with the result of antioxidant ability,the supplemented amount of UGSP would be 10% and 15%.