In order to investigate the thermal aggregation behavior of myosin at different Ca2+ concentrations, the myosin was extracted from longissimus dorsi muscle of pigs. By adding different concentrations of calcium chloride (0.01mol/L, 0.02mol/L, 0.03mol/L, 0.04mol/L, 005mol/L, 0.075mol/L and 0.1mol/L), the changes of morphology and structure of aggregates during the heating process and gel properties were studied by means of thermal denaturation kinetics, differential fluorescence scanning instrument and negative staining transmission electron microscope. The aim was to elucidate the mechanism of myosin thermal aggregation in pork. The results showed that the concentration of Ca2+ was increased from 0.01mol/L to 0.1mol/L, the denaturation temperature of protein was decreased from 40.2℃ and 52.4℃ to 36.5℃ and 508℃, the thermal stability of myosin was decreased significantly (p<0.05);with the increase of temperature and calcium chloride concentration, the turbidity, particle size and denaturation rate of myosin were increased gradually;the activity of Ca2+-ATPase was increased significantly (p<0.05) at the initial state of myosin, and the temperature of myosin binding to form aggregates was decreased. Electron microscope observation showed that the higher the concentration of Ca2+ was, the faster the aggregation rate was. Under the concentration of 0.1mol/L CaCl2, the volume of protein aggregates was increased significantly to form disordered aggregates. The concentration of Ca2+ was increased from 0.01mol/L to 0.1mol/L, and the gel strength was increased from 4.58N to 5.28N. Gel strength of 80℃ and 0.1mol/L calcium chloride treatment group was significantly (p<0.05) higher than other treatment groups. Therefore, with the increase of temperature and calcium chloride concentration, pork myosin aggregates were easy to form and the gel strength was increased.