Abstract: The purpose of this study was to investigate swelling kinetics and stability of gelatins with different gel strengths，as well as the component which might affect gel strength and cross-linking reactivity.SDS-PAGE assay was undertaken to determine the content of gelatin components - α，β and γ component which were isolated through CM52 cation exchange column ，and the cross-linking activity of the components was determined by the formaldehyde cross-linking simulation study.At the same time，the equilibrium swelling ratio (S_eq) and ε-amino acid residue content indicative of the swelling kinetics and the stability of cross-linking were assessed according to the methods reported in the literatures.It was shown that the increase in α- component led to the corresponding increase in the gel strength of gelatin but the decrease in the equilibrium swelling ratio.The ε-amino acid residue contents of α，β and γ components decreased in the order of α> β> γ.It was found that the gel strength increased as the ε-amino acid content did .Accelerating study showed that instability-indicative cross-linking could occour in the gelatin with higher gel strength during storage.