Polyvinyl alcohol/sodium alginate (PVA/SA) hydrogels were prepared by using PVA and SA as raw material. The PVA/SA hydrogels were chemical crosslinked with calcium chloride/boric acid solution, and physical crosslinked by cyclic freezing and thawing. The cross-linking mechanism, mechanical properties, water content, porosity and cell compatibility of hydrogels were analyzed. FT-IR results show that, after cross-linking with CaCl₂/ boric acid solution, Ca²⁺ forms complexation with 的-COO^- in SA, B(OH)₄^- in boric acid solution is crosslinked with PVA, and the cyclic freezing and thawing promote the formation of intermolecular and intramolecular hydrogen bonds in the composite hydrogels. SEM results show that the PVA/SA hydrogels exhibit a porous structure inside with a pore size of about 5～30 μm. When the PVA/SA mass ratio is 8∶2 and the crosslinking agent mass fraction is 5%, the compression modulus and compressive strength of hydrogels reach (121.84±3.03) kPa and (636.18±68.71) kPa, respectively. Meanwhile, the water content and porosity reach 83.73% and 79.98%,respectively. The PVA/SA hydrogels show good cytocompatibility based on the results of co-culture with cells.