The effects of different concentrations of gallic acid (0， 1， 2， 4， 6 mg/g) with the aid of ultrasound on the structural properties of myofibrillar proteins of Lateolabrax japonicas were investigated. The structure and gel information through Raman spectroscopy， endogenous fluorescence spectroscopy， surface hydrophobicity， differential calorimetric scanning (DSC)， dynamic rheology， molecular mass were analyzed. The results showed that ultrasound and gallic acid addition could change the secondary structure of myogenic fibronectin in Lateolabrax japonicas. The α-helix content of myogenic fibrillar protein increased from 52.81% to 74.68% and β-folding decreased from 21.3% to 5%. When the addition of gallic acid increased from 0 mg/g to 2 mg/g without ultrasound treatment， the β-turn and irregular curl content decreased； when the gallic acid content continued to increase， the α-helix content showed a decreasing trend. After ultrasonic treatment， the α-helix content increased further， and the highest α-helix content reached 80%， when the gallic acid was added at 2 mg/g. Meanwhile， with the increase of gallic acid， the tertiary structure and gel properties of proteins were changed， the fluorescence intensity was decreased， but the surface hydrophobicity was significantly increased (P < 0.05). In addition， the thermal denaturation temperature of myofibrillar proteins， and the enthalpy change and rheological properties were also increased， which showed that ultrasound-assisted gallic acid could change the structure of proteins， thus promoting the formation of more viscoelastic gels of myofibrillar proteins. The protein structure was changed by ultrasound-assisted gallic acid， thus promoting the formation of a more viscoelastic gel network structure， which led to the improvement of protein gel properties.