CdS is a photocatalyst known for its desirable bandgap and availability but it is limited by photocorrosion and inefficiency issues in practical applications. According to band engineering theory, regulating the width of bonding region that exists between cubic phase and hexagonal phase, we design a suitable phase junction and achieve effective separation of electron-hole pairs. Thus, the problems caused by photocorrosion and phase exclusion can be resolved. The optimal photocatalytic activity of the prepared material is 4.9 mmol h(-1) g(-1) with 41.5% quantum efficiency at the wavelength of 420 nrn, Which is 60 times higher than that of the initial samples (cubic or hexagonal phase), and keeps high photocatalytic stability. This novel construction approach can be useful in designing ideal band structures and matching the phase bandgap of other binary sulfides.