Polyvinyl alcohol/chitosan (PVA/CS) composite hydrogel were prepared by freeze-thaw method and soaking sodium citrate (Na3Cit) aqueous solution. The structures and morphologies were characterized by FTIR, XRD, DSC and SEM, and the mechanical properties were tested. The results showed that PVA single network hydrogel had a mesh size between 1.5 μm and 8.2 μm, free water content (FW) of 76.2% and effective cross-linking density (v0) of 0.0288 mol/L. After introducing CS into PVA single network and soaking Na3Cit, the mesh size and FW of the prepared PVA/CS composite hydrogel decreased to 1.5 μm and 1.45%, and the v0 increased to 0.421 mol/L. While the tensile strength and compressive strength were 9.3 MPa and 16.6 MPa, respectively. This was attributed to the synergistic cross-linking of hydrogen bonds and ionic bonds of composite hydrogels. At the same time, the composite hydrogel exhibited excellent anti-fatigue and swelling-resistant properties. The compressive strength and toughness of the composite hydrogel after 10 successive compression tests were 88.1% and 84.3% of their original values. Furthermore, the tensile strength after reaching a swell-equilibrium in deionized water was 4.3 MPa.