Abstract: In this paper,the combination between collagen polypeptide and calcium gluconate was studied based on the preparation of collagen polypeptide from pigskin gelatin by measuring chelate rate. Plackett-Burman(PB) design and central composite design(CCD) were applied to screen and optimize 7 factors(solidliquid ratio,ratio of collagen polypeptide to calcium gluconate,p H,reaction temperature,reaction time,agitation speed and mixing time) for the calcium binding capacity. The ratio of collagen polypeptide to calcium gluconate,p H and the reaction time were the main factors of chelated calcium by PB design. The optimal chelate condition was determined as : ratio of collagen polypeptide to calcium gluconate 5. 5 ∶ 1( W / W), p H6. 0, reaction time130 min,solid-liquid ratio 1.5∶100,reaction temperature 60 ℃,agitation speed 30 r/min,and mixing time 20 min and the chelate rate of Ca-collagen polypeptide could reach 78.3%. The structure of chelated calcium was characterized by the UV-VIS,FT-IR,SEM and X-ray. The research confirmed the chelating reaction between calcium ion and collagen polypeptide,and the coordination reaction between calcium and carboxyl/amino group of collagen polypeptide occurred.