Sea bream back muscles were thawed using microwave thaw （MT）， far infrared thawing （FT）， chitosan magnetic nanomicrowave thaw （CMT）， and chitosan magnetic nano-far infrared thaw （CFT）， respectively. The thermal stability and viscoelasticity were applied to DSC and dynamic rheology. Myofibrillin from fish block muscle was extracted to determine Raman spectroscopy， UV absorption spectrum， intrinsic fluorescence spectrum， and particle size， analyzing the spatial conformation and aggregation of proteins. The water distribution and microstructure were determined by using low-field NMR techniques and SEM. The results show that the CMT treatment has the lowest juice loss rate， which effectively maintains the hardness， elasticity and viscosity of the fish， and can form a relatively ideal and stable network structure. Meanwhile， its myofibrulin solution structure is relatively stable. Both CFT and CMT treatments retain a tightly ordered microstructure and overall a more stable tertiary structure than FT and MT treatments， slowing protein oxidation while maintaining strong system stability. Therefore， CMT and CFT treatment can be used to improve protein physicochemical properties during thawing.