Objective: Explored the composition and content of phenolic compounds in tartary buckwheat wine lees, and study their antioxidant activity. Methods: Phenolic compounds in tartary buckwheat wine lees were analyzed by HPLC and LC-MS. And evaluating its antioxidant activity. Results: 7 phenolic compounds were identified from tartary buckwheat wine lees, including 5 flavonoids, with the highest content of rutin of （9.350±0.050） mg/g, followed by quercetin, isoquercetin, kaempferol-3-o-rutoside and kaempferol of two phenolic compounds. At 0.5 mg/mL, the scavenging rates of hydroxyl free radical, ABTS⁺ and DPPH free radical reached （73.29±0.09）%, （96.21±0.25）% and （82.55±0.68）%, respectively, with FRAP value of （2.49±0.09） mmol/L. Conclusion: The fermented tartary buckwheat lees are rich in phenolic compounds, and the lees extracts has certain antioxidant activity. In addition, at low concentration, the tartary buckwheat wine lees also showes good scavenging effects on hydroxyl radical and ABTS⁺ radical.