Chlorella sorokiniana is an edible microalga known for its high protein content with a balanced amino acid composition, nutritional value, beneficial health effect, and natural antioxidant. The enzymatic assays was used to extract the peptides of C. sorokiniana which was an uncommon method to test the antioxidant activity. In this research, protein of C. sorokiniana was extracted, purified, and hydrolyzed in several enzymes and kept at 37 C for 16h. Hence, enzymatic hydrolysate< 3kDA was fractionated into 11 portions (C0%, C10%, to C100%) by using offline Strong Cation Exchange Chromatography (SCX) and their antioxidant activity was tested using DPPH (2.2-diphenyl-1-picrylhydrazyl) radical scavenging assay. The results indicated that C80%, contributed to the highest free DPPH scavenging on C. sorokiniana hydrolysate with the inhibition of 22.04%. Furthermore, to find the candidate peptides, this fraction was injected into LC-MS/MS for characterization of it's DPPH inhibitation. LSSATSAPS (m/z 1638, 78) and AGLYGHPQTQEE (m/z 1328.59) are peptides that were identified and confirmed by LC-MS/MS. The molecular docking study was conducted to provide the binding simulation between these peptides and the ROS1 as the receptor. In conclusion, our results suggested that the aforementioned peptides were attached to ROS1 binding site and contributed to its potential antioxidant activity.