Abstract: In this paper, sea bass (Lateolabrax maculatus) were uesd as raw material to study the effect of ultrasound on the structure and functional properties of myofibrillar proteins in sea bass by the different ultrasonic power in the range of 0~540 W and time at 0~12 min. The results showed that, with the extension of the ultrasonic time and power, the sulfhydryl content of myofibrillar protein decreased, while the UV absorbance increased, and the α-helix content had a tendency to transform into β-sheets, β-turns and random coils. Ultrasound at 180~450 W, particle size and turbidity of myofibrillar protein were reduced, the solubility was improved. Ultrasonic treatment improved the rheological properties of myofibrillar and increased the G' and G" in the thermally induced gel process. Principal component and cluster analysis showed that different ultrasonic power and time had a greater impact on the physical and chemical properties of myofibrillar protein. These findings suggested that ultrasound altered the structure of myofibrillar proteins in sea bass, which affected rheological properties and contributed to better functional performance.