Ni2P/ZnS and Ni2P/CdS core/shell composites were synthesized using a simple two-step route at a low temperature. We used X-ray powder diffraction, scanning electron microscopy, energy dispersive spectroscopy, and so on to characterize their composition, structure, and morphology. The characterized results show that Ni2P/ZnS and Ni2P/CdS core/shell composites consist of Ni2P microsphere core and ZnS (or CdS) nanostructure shell, and CdS nanorods and ZnS nanoparticles are deposited on the surface of Ni2P microspheres, respectively. Then choosing methylene blue (MB) as a typical organic dye, the photocatalytic degradation activities of Ni2P/ZnS and Ni2P/CdS are investigated, which exhibit a good photocatalytic activity. When the concentration of MB solution is 1 × 10−5 mol/L and the mass of the added photocatalyst is 0.05 g, it is found that two composites have enhanced photocatalytic degradation ratios (89 and 78%) compared to that of Ni2P microsphere (65%), which might be due to the effective separation of photogenerated electron-hole pairs.