Objective: To evaluate the potential of cellulose nanocrystals (CNC) as a novel cryoprotectant for improving the quality of frozen surimi. Methods: The ice recrystallization inhibition (IRI) activity of CNC was determined using the splat assay. Different mass fractions of CNC (1%， 3%， 5%) were added to grass carp surimi. The myofibrillar protein (MP) content， SDS-PAGE pattern， total sulfhydryl content， and water-holding capacity were measured at various frozen storage times (0， 10， 20， 30 d， and 40 d). The viscoelastic properties of surimi gels were evaluated by dynamic rheological analysis. Results: CNC exhibited excellent IRI activity with a dose-dependent effect. In the 0.5% CNC treatment group， ice crystal sizes were concentrated in the range of 14-20 μm with a uniform distribution， whereas ice crystals in the negative control group were mostly concentrated in the range of 100-120 μm. After 40 d of frozen storage， the MP content， total sulfhydryl content， and water-holding capacity of surimi in the 5% CNC group remained at 2.43 mg/mL， 48.14 μmol/g， and 80.54%， respectively， all significantly higher than those in the NC group (1.39 mg/mL， 31.10 μmol/g， and 68.27%) (P < 0.05)， indicating that CNC effectively delayed the quality deterioration of frozen surimi during storage. The rheological properties of surimi gels were significantly better than those of the control group， with markedly increased storage modulus (G′) and gel strength. Conclusion: By inhibiting ice crystal growth and recrystallization， CNC protects the structural and functional integrity of proteins， effectively alleviates protein denaturation in frozen surimi， and improves its water-holding capacity and gel properties. CNC thus shows promise as an efficient， calorie-free， non-sweet cryoprotectant.