Flower-like ZnS microspheres are synthesized by a simple one-step solvothermal method using zinc acetate and thiourea as raw materials, and then oxidized at high-temperature 550℃，600℃ and 650℃, respectively. The crystal structures, morphologies, compositions, specific surface areas and optical properties of the samples are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), automatic surface area analyzer, Raman spectrometer (Raman) and UV-Vis absorption spectrum. Moreover, photocatalytic activities are evaluated by degradation of RhB solution. The results show that the samples synthesized in situ are ZnS microspheres with cubic phase. After 1 hour high-temperature oxidation of the samples at 550℃, a small amount of ZnO is observed due to the penetration of oxygen atoms and type-II ZnS/ZnO heterostructures are formed after one hour oxidation at a high temperature of 600℃.When oxidation at the highest temperature of 650 ℃ for 1 hour, the samples nearly become the ZnO component. With the increasing of oxidation temperature, the energy gap decreases in overall. Finally, the photocatalytic activity presented that fabricated ZnS/ZnO heterostructures showed best photcatalytic performance.The degradation rate of RhB reached 98.5% after 40 minutes of UV irradiation.