Taking walnut oil as the test material, its antioxidant activity in the storage process was studied. The results showed that unoxidized walnut oil showed good antioxidant ability. The inhibition rate of walnut oil on DPPH· radical increased with the increase of the concentration of walnut oil. The inhibition rate of walnut oil on DPPH· reached 50% when the concentration of walnut oil was 147.0 mg/mL; the inhibition rate of walnut oil on OH· reached 50% when the concentration of walnut oil was 340.83 mg/mL; the average inhibition rate of walnut oil and VC on O₂^.- was almost in the same level when the concentration of walnut oil and VC was 1.0mg/mL. The inhibition rate of walnut oil on DPPH· and OH· decreased obviously after it was oxidized. The scavenging activity of walnut oil in the same concentration oxidized for different time on superoxide anion radical (O₂^.-) declined gradually with the increase of the time. The average inhibition rate of walnut on O₂^.- dropped from 55.53% to 15.43% after 30 days being oxidized. In a word, the unoxidized walnut oil had good antioxidant ability. However, their antioxidant ability decreased as oxidation time increased.