Abstract: The study aimed to establish the effective extraction methods for Chlamydomonas reinhardtii proteins and screen peptide segments with inhibitory effects on monoamine oxidase A (MAO-A). The proteins were extracted, separated, and purified by swelling, ultrasonication, alkaline dissolution, and salting-out. Subsequently, the polypeptide content, amino acid composition, molecular weight distribution and the MAO-A inhibitory effect of proteins treated with enzymatic hydrolysis and ultrafiltration were determined. Peptide sequences with high inhibitory potential were selected by bioinformatics tools and molecular docking with MAO-A was applied to analyze the binding sites. The results indicated that a protein extraction yield of 50.98%±2.50% was achieved through swelling for 4 h, followed by four cycles of 240 W ultrasonication (10 min per cycle), alkaline dissolution at pH9.5, acid precipitation at pH3.5, and the treatment with saturated ammonium sulfate at a ratio of 1:2. Notably, the alkaline protease hydrolysate (APH) and neutral protease hydrolysate (NPH) exhibited high inhibitory effects on MAO-A (P<0.05), with IC₅₀ values of 3.437 and 2.699 mg/mL, respectively. The fractions with molecular weights less than 3 kDa from APH and NPH (APH-Ⅲ and NPH-Ⅲ) displayed significantly higher MAO-A inhibitory effect (P<0.05), with IC₅₀ values of 3.116 and 0.909 mg/mL, respectively. Molecular docking results showed that two peptides, ASDDAVHGWGGPGGY and AYSGETQSEGGFAPNR from NPH-Ⅲ, could effectively bind to the active sites His488, Glu286, Tyr53, Tyr268, Asp343 and Glu485 of MAO-A.