Abstract: Sea cucumber Stichopus japonicus has become an important cultivated aquatic species in China in recent years.Previous studies mainly focused on the food sources,nutrition values,biological activity and structure of acid polysaccharide.However,these studies do not have a tissue structural consideration on sea cucumber meat.In this paper,the changes of muscle tissue and collagen fibers structure from S.japonicus during heated treatment were studied,and the variation mechanism was analyzed.The structures of muscle tissue and collagen fibers were observed by a light microscope and a scanning microscope,meanwhile DSC tested the denaturation temperature of sea cucumber.Following were the results.The changes of tissue structure and collagen fibers after heating treatment were evident.Along with the increasing of heating temperature,the muscle fibers gradually aggregated and cross-linked,forming porous mesh structure.The collagen fiber structure shrunk,accompanied with collagen protein denaturation leading to fibers closely spaced.The changes of collagen fibers structure were more prominent compared with the overall tissue structure.DSC scanning curve of rawS.japonicus meat showed the denaturation temperature was 68.92 ℃.Thermal denaturation of muscle protein during heating treatment resulted in the changes of tissue structure and collagen fibers.