A novel polyoxometalate (POM)-based metal-organic framework, TBA5[P2Mo16VMo8VIO71(OH)9Zn8(L)4] (NNU-29), was in situ synthesized and applied into CO2 photoreduction. The selection of porous material containing a reductive POM cluster is considered to be helpful for CO2 reduction; meanwhile, a hydrophobic-group-modified organic ligand enables NNU-29 to exhibit good chemical stability and restrains hydrogen generation to some extent. In the photocatalytic CO2 reduction, the yield of HCOO– reached 35.2 μmol in the aqueous solution with selectivity of 97.9% after 16 h.