Abstract: Shrimp surimi products commonly suffer from insufficient gel strength and poor water holding capacity, and single transglutaminase (TGase) treatment presents limited modification effects. Nano-shrimp-shell calcium (NSSC) prepared from shrimp shell by-products possesses calcium ion bridging and water regulation functions. This study compounded NSSC with TGase to explore their synergistic effects on the gel properties and flavor characteristics of shrimp surimi, providing a basis reference for shrimp surimi quality improvement and high-value utilization of shrimp shell by-products. With TGase addition fixed at 0.4% (w), NSSC was supplemented at concentrations of 0.01%–0.08% (w) to prepare shrimp surimi gels. Multiple methods, including texture profile analysis, low-field nuclear magnetic resonance, rheological determination, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and gas chromatography-mass spectrometry (GC-MS), were used to systematically investigate the properties of the gel, water distribution, changes in the secondary structure of proteins, micromorphology and changes in volatile flavor components. The results showed that the addition of NSSC had a significant effect on the performance of shrimp surimi gel (p<0.05). When the amount of addition reached 0.06%, the hardness, chewiness and water retention of the gel improved. The α-helix in the secondary structure of the protein was transformed into β-folding, and the network structure also became tight. When the amount of addition increased to 0.08%, the ductility of the gel was enhanced, the hardness decreases, and the intensity of the gel increased. It is speculated that it was related to the local aggregation after the overdose of nanoparticles. Flavour analysis showed that among all additions, the signal strength of 0.02% group fishy aldehydes and 1-octen-3-ol was significantly lower than that of the control group, with the best sensory score, while the proportion of 0.06% group aldehyde ketone oxidation products increased significantly, and the flavour spectrum tends to be complicated. Therefore, NSSC and TGase can effectively improve the quality of shrimp surimi gel. Their mechanism of action is physical filling, Ca²⁺ chemical regulation and changes in protein conformation. From the perspective of texture properties, 0.06% is more suitable for the addition, and the optimal addition at flavor level is 0.02%. The optimal addition of the two is not the same, and the relationship between quality composition, color and flavor needs to be considered in actual use.