Stickwater　and　oyster　shells　can　be　used　as　cost-effective　sources　to　produce　high-value　peptide-calcium　chelate.　In　this　study,　the　optimal　preparation　process　of　chelate　from　peptides　of　stickwater　hydrolysate　and　calcium　of　oyster　shells　was　determined　by　response　surface　methodology,　under　which　a　high　calcium　chelation　rate　of　87.62%　was　achieved.　The　analysis　of　peptides　sequence　showed　that　all　chelated　peptides　were　from　the　myosin　light　chain,　and　the　molecular　weight　of　most　of　them　was　lower　than　1500　Da.　There　were　19,　20,　and　19　of　the　26　chelated　peptides　containing　Glu,　Asp,　and　Gly　residues,　respectively,　which　have　been　proved　to　exhibit　high　calcium-binding　ability　in　previous　studies.　Structural　characterizations　revealed　that　–NH2,　COO-,　N–H,　C[dbnd]O,　C–H,　and　–OH　groups　might　participate　in　the　formation　of　peptide-calcium　chelate,　and　new　interaction　forces　of　crystal　structure　were　generated　in　the　chelate.　Besides,　morphology　analysis　showed　that　folded,　aggregated,　and　compact　structures　formed　in　the　peptide-calcium　chelate.　Moreover,　the　peptide-calcium　chelate　was　relatively　stable　under　high　temperature　and　digestion　conditions　in　the　gastrointestinal　tract,　indicating　that　it　could　be　used　as　a　highly　effective　calcium　supplement.　©　2022　The　Authors