Resistant and susceptible soybean varieties were inoculated with Soybean Mosaic Virus(SMV). The seeds were taken for biochemical analysis. The result showed that both peroxidase(POD) and polyphenoloxidase(PPO) activities in seed coat of uninoc ulated resistant varieties were much higher than that of uninoculated susceptible varieties. Superoxide dismutase(SOD) activity in seed coat of uninoculated resistant varieties was a little stronger than that of susceptible varieties. There were two bands of PPO and three bands of POD in uninoculated resistant varieties more than that in susceptible varieties. After inoculated with SMV,POD activity was increased a little in susceptible varieties. Both POD and PPO activities were rapidly decreased in seed coat of resistant varieties after inoculated with SMV and one band was vanished. SOD activity was increased in suscepti ble varieties after inoculated with SMV, while remain stable in resistant varieties. The seeds were taken for biochemical analysis. The result showed that both both peroxidase (POD) and polyphenoloxidase (PPO) activities in seed coat of uninoc ulated resistant varieties were much higher than that of uninoculated susceptible varieties. a few stronger than that of susceptible varieties. there were two bands of PPO and three bands of POD in uninoculated resistant varieties more than that in susceptible varieties . After inoculated with SMV, POD activity was increased a little in susceptible varieties. Both POD and PPO activities were rapidly decreased in seed coat of resistant varieties after inoculated with SMV and one band was vanished. SOD activity was increased in susceptible varieties after inoculated with SMV, while remain stable in resistant varieties.