By adding dimethyl sulfoxide (DMSO), nano titanium dioxide (TiO2) and sodium carbonate (Na2CO3) to polyvinyl alcohol (PVA), the PVA-TiO2 composite hydrogel membrane with high mechanical properties and photocatalytic ability was prepared using the freeze–thaw cycle method. The addition of DMSO and TiO2 can effectively improve the mechanical strength of the composite hydrogel membrane and its photocatalytic degradation efficiency of dye. By optimizing the raw material ratio and preparation process, the tensile strength of the prepared composite membrane can reach 14.3 MPa, which is the highest among the reported membrane of its kind. The maximum tensile toughness is 8.16 MJ/m3, indicating the good ductility. The maximum adsorption capacity of methylene blue (MB) calculated from Langmuir isotherm model is 318.47 mg/g and after 4 d nature light treatment, the dye removal rate can reach 99.85%. © 2021 Elsevier B.V.