Abstract: To maintain the stability of oyster peptides (OEH) and enhance their slow-release effect, oyster peptide microcapsules were prepared by ionotropic gelation method using oyster peptide as the core material and sodium alginate (SA) as the wall material. The preparation process of single-layer microcapsules (OEH-SA) was optimized using single-factor and orthogonal experiments, with encapsulation efficiency as the evaluation index. Based on the OEH-SA microcapsules, chitosan (CS) was used as an additional wall material to prepare double-layer microcapsules (OEH-SA-CS). The encapsulation efficiency, drug loading, moisture content, and swelling rate of OEH-SA and OEH-SA-CS were compared. Both microcapsules were characterized using inverted microscopy (IM), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). The slow-release rate and antioxidant activity during release were also evaluated. The results showed that the optimal preparation conditions for OEH-SA were 1.5% sodium alginate, 3% calcium chloride, 0.1% Tween 80, and a curing time of 20 min, yielding an encapsulation efficiency of 82.69%. The OEH-SA-CS microcapsules prepared with 1% chitosan exhibited a release rate of 52.49% after 5 hours of in vitro simulated digestion, with DPPH and ABTS⁺ radical scavenging rates of 23.9% and 42.8%, respectively. Compared to OEH-SA, OEH-SA-CS exhibited a better slow-release effect and maintained a longer antioxidant activity. The microencapsulation process used in this study was simple, achieved good encapsulation efficiency, and the prepared microcapsules showed a certain slow-release effect in gastrointestinal simulated digestion, which was conducive to the functional activity of OEH. The results of this study can provide a theoretical basis for the high-value utilization of oyster peptides.