In this paper, defatted pea protein was enzymatically digested using compound protease (alkaline protease : flavored proteas =3 : 1). The enzymatic hydrolysates were separated and purified via ultrafiltration membrane tubes (3kDa, 1kDa) with Sephadex G-15 chromatography, and the fraction P2 with the highest antioxidant activity and practical application was obtained. The de novo sequencing based on Nano LC-MS/MS combined with professional online tools was adopted to predict peptide sequences, and five novel unreported peptide sequences designated F1-F5 were identified. Finally, solid-phase synthesized peptides were added to walnut oil. The Schaal oven accelerated test was used to investigate the oxidative stability of walnut oil at different storage stages. By determining the peroxide value, acid value, DPPH radical scavenging rate, hydroxyl radical scavenging rate, ABTS radical scavenging rate, total phenolic content, synchronous fluorescence spectra and conducting shelf-life prediction, the effect of defatted pea antioxidant peptides on delaying the rancidity of walnut oil was evaluated. The results showed that F1, F4 and F5 exhibited significant effects on delaying the peroxidation of walnut oil, improving radical scavenging rate and inhibiting the loss of endogenous antioxidant substances (P<0.05), and extended the shelf life of walnut oil to more than 50 days. Therefore, F1, F4 and F5 were identified as potent antioxidant peptides with great significance for improving the oxidative stability of walnut oil. This study preliminarily verified that pea antioxidant peptides can reduce oxidative deterioration of walnut oil, improve the comprehensive utilization value of peas.