Abstract: The antioxidant activity of Zanthoxylum armatum DC Prodr.Oil was evaluated through building antioxidant experiment model in vitro. To evaluate the antioxidant potengtial of Z. armatum DC Prodr. Oil, the abilities of Z.armatum DC Prodr.Oil to scavenge DPPH radicals, superoxide anion radicals, and hydroxyl free radicals, and its reducing power were assayed with vitamin C and BHT as the positive control. Results showed that the reducing power, the hydroxyl free radicals, DPPH radicals, superoxide anion radicals scavenging capacity increased gradually with the increasing of the mass concentration.The scavenging ability on hydroxyl free radicals and DPPH radicals of the cold presssed oil was weaker than that of the oil extracted from absolute ether besides its ability against superoxide anion radicals at the same concentrations. The mass concentration that cold presssed oil scavenged half of hydroxyl free radicals, DPPH radicals, superoxide anion radicals was determined to be 4.0675, 10.3052, 0.5415 mg / m L, respectively. While the oil extracted from absolute ether was determined to be 1.9606, 2.9465, 1.6053 mg / m L, respectively.The scavenging rates of 9mg / m L oil extracted from absolute ether on hydroxyl free radicals was 89.79%, which was equal with 1mg / m L vitamin C.The scavenging rates of 11 mg / m L oil extracted from absolute ether on DPPH radicals was 86.87%, which was better than 1mg / m L BHT.