The cauliflower-like ZnS microspheres consisting of the nanospheres were prepared via one step template-free approach employing a solvothermal process using Zn(NO3)2·6H2O and CH4N2S as precursors in the mixture solution. The morphology, structure characterization, and crystal structure of the as-prepared ZnS were performed by X-ray diffraction, scanning electron microscopy, UV-visible absorption, and X-ray photoelectron spectroscopy. The results showed that cauliflowerlike ZnS microspheres were prepared under this condition and the size of the particles were about 3~5 μm. In addition, the excellent photocatalytic activity and degradation mechanism of ZnS microspheres have been investigated and discussed in detail. The degradation of Rhodamine B (RhB) aqueous solution was carried out to investigate the visible-light catalytic activity under metal halide lamp. The results indicated that different size of ZnS had photocatalytic activity to RhB under visible light, and sphere-like ZnS displayed high photodegradation efficiency with degradation rate of 98% within 140 min.