Objective: This study aimed to make full use of walnut by-products. Methods: Ultrasonic-assisted ethanol extraction method was used to extract the antioxidant components of walnut shell and distraction wood. The changes of antioxidant components (total phenols and total flavonoids) and antioxidant activities (DPPH, ABTS, hydroxyl radical scavenging ability, Iron reduction antioxidant capacity-FRAP and ferrous ion chelating activity) of walnut by-products extract during the simulated digestion were studied in vitro, and their correlation was analyzed. Results: The total phenols(TPC), total flavonoids(TFC) content, and antioxidant activity of distraction wood were always higher than those of walnut shells (P＜0.05). After simulated in vitro digestion, the TPC and TFC of both walnut shell and distraction wood decreased gradually (P<0.05). The antioxidant capacity of FRAP and DPPH, ABTS+ free radical scavenging capacity were approximately as follows: oral>stomach>intestine (P<0.05), a trend consistent with the changes of TPC and TFC. Except for Fe²⁺ chelating activity, the antioxidant capacity of the digestive juices showed a significant positive correlation with TPC and TFC (P<0.05). Conclusion: Distraction wood extract has an impressive antioxidant activity which was superior to walnut shell extract and was expected to be used as a natural antioxidant functional food or raw material source of antioxidants.