Myosin was extracted from tilapia muscle, the changes of turbidity, solubility, surface hydrophobicity and sulfhydryl content of myosin under different salt concentration (1, 50,150, 600 mmol/L NaCl) were investigated. The heat-induced myosin gel was prepared and the formation and mechanism of thermal gel was discussed. Results showed that with the increasing of ionic strength, solubility of myosin gradually increased and turbidity decreased with the increasing of the surface hydrophobicity and -SH content. The solubility showed a significant downward (p<0.05), while the surface hydrophobicity was increased (p<0.05) and sulfhydryl content was decreased with heat treatment from 20 to 80 ℃ at 1 ℃/min., which indicated thermal denaturation and aggregation of myosin happened. Heat-induced dynamic elastic modulus of myosin dispersion increased with the increasing of salt concentration. Main force of three-dimensional network structure stabilized gel structure was hydrophobic interaction, disulfide bonds and non-disulfide covalent bond. Myosin gelation network structure is more stable under high ionic strength condition.