Abstract: In this paper, the effects of natural deterioration of tree peony seed under two storage periods on the quality of seed oil by supercritical CO₂ extraction of tree peony seeds were analyzed. The results showed that compared to newly harvested seeds, oil from naturally aged seeds stored 12 months under room temperature had a darker color, significantly increased contents of acid value, peroxide value, and AFB1, markedly decreased content of vitamin E, marginally increased the Ba P content under the edible vegetable oil safety standards of China, but not clear change in fatty acid composition and contents.These results suggested that the storage period of oil tree peony seeds should be shortened in order to avoid poor oil quality of tree peony seed and increase risk to health.