This study was compare of physics and chemical property of Styrene-butadiene-styrene (SBS)/ Acrylic acid (AA) copolymer after thermal polymerization and UV graft-polymerization. The result of this study shows: when the thermal polymerization was used, the grafting percentage of SBS-g-AA rose along with the increase of the AA monomer concentration. The maximum occurred when SBS=0.5g and AA=2.5 x 0.0065mol, then it decreased along with the increase of the AA concentration. The transition ratio and grafting percentage decreased as the concentration of SBS increased; while AA was fixed on 0.0065mol, the maximum grafting percentage occurred by using 1g SBS. The grafting percentage increase along with the increase of reacting time, and it reached the maximum after reacting 3 hours. The water contact angle was lowered from 82o to 58o. Using the UV graft-polymerization, when AA monomer concentration increased, the grafting percentage increased as well; the maximum occurred when AA concentration was 2.88M. Moreover, the grafting percentage was increasing along with the increase of reacting time, but it stopped increasing around 40 minutes reacting time. The grafting percentage of thermal polymerization was higher than UV graft-polymerization. It shows that the swelling ratio of membranes grafted using the UV light was higher than those grafted by thermal polymerization.