Enabling the photogenerated electron-hole separation of visible light responsive photoanode is essential to the conversion and utilization of solar energy in the photoelectrochemical (PEC) water splitting. In this study, porous CdS/CdO-M heterojunction photoanodes on fluorine-doped tin oxide glasses were prepared by calcining the Cd-metal-organic framework (Cd-MOF) and loading the CdS via successive ionic layer adsorption and reaction method. The heterojunction and pores in these prepared photoanodes promoted the separation and transfer of photogenerated electron-hole in the PEC water splitting. The optimized photoanode (CdS/CdO-M-15) exhibited superior photoelectrochemical water splitting performance with a photocurrent density of 4.8 mA cm⁻², which is 20, 6 and 1.5 times higher than that of CdO-M, CdS and CdS/CdO-C-15 (prepared by the commercial CdO). The applied bias photon-to-current conversion efficiency of CdS/CdO-M-15 was as highly as 4.5% under simulated solar light of 100 mW cm⁻² in 0.25 M Na₂S + 0.35 M Na₂SO₃ aqueous solution. Moreover, CdS/CdO-M-15 was stable under continuous illumination, and its photocurrent density for it was well maintained after 1 h illumination.