The changes in physiochemical properties of myofibrillar protein from crucian carp during heattreatment were studied through the tests of turbidity,viscosity,Ca²⁺-ATPase activity,total sulfhydryl content and a SDS-PAGE study.Research on changes in physicochemical properties of myofibrillar protein during heattreatment can help to understand the thermal denaturation of it and provide practical information for crucian carp muscle processing,so as to promote the utilization of huge amount of freshwater fish resources in China.The results showed that turbidity increased as temperature rose.Turbidity did not show a significant increase from 20 to 34 ℃.With increasing temperature from 36 to 70 ℃,turbidity increased significantly and three peaks of change rate was observed at 36,42 and 48 ℃.No significant shifts were detected when the temperature became above 70 ℃; Viscosity declined from 20 to 47 ℃,and two peaks of change rate were observed at 35 and 47 ℃.No significant shifts were detected when the temperature became above 47 ℃.Ca²⁺-ATPase activity decreased from 28 to 40 ℃,at the first stage(28-34 ℃),Ca²⁺-ATPase activity decreased slowly,then,from 34 to 40 ℃,Ca²⁺-ATPase activity decreased significantly and one peak of change rate was observed at 36 ℃.At 40 ℃ Ca²⁺-ATPase activity reduced to zero.Sulphydryl content decreased in ranges 20 to 28 ℃ and 40 to 68 ℃ and kept a certain value at 68 ℃ with a slight increase from 28 to 40 ℃.Electrophoretic analysis indicated high temperature(≥40 ℃)induced disulfide bonding between myosin chains and other proteins and formed macromolecular substances.