Abstract: In this study, we focused on the preparation of hydrogels with good biocompatibility of sodium alginate (SA), chitosan (CS), and calcium carbonate (CaCO₃) by physical cross-linking. We aimed to optimize the hydrogel formulations and systematically explore their structure, physical properties, and freeze-thaw stability. The optimal formula was determined using a single factor experiment and response surface method: SA concentration was 2.14%, CS concentration was 1.7%, Ca²⁺ concentration was 0.31 mol/L, and the hydrogel swelling rate was 17.20%. The freeze-thaw experiment showed that the performance of the hydrogel was significantly improved while freezing at −80 ℃ and thawing at 4 ℃, and the best effect of one freeze-thaw cycle was achieved: the hardness increased from 125.3 g to 189.6 g, the elasticity increased from 0.72 to 0.85, and the storage modulus increased from 2100 Pa to 3500 Pa. There was a minimal decrease in performance after the second cycle. Nuclear magnetic resonance analysis showed that the hydrogel was more water-bound and more stable in structure under these conditions, and Fourier transform infrared spectroscopy confirmed that the hydrogel was physically cross-linked. The dual-network hydrogels prepared in this study have excellent mechanical properties and freeze-thaw stability, which provides an important theoretical basis and practical reference for their application in frozen food preservation and as biomedical carriers.