ZnS pillared kaolinite_montmorillonite (ZnS-PKM) nanocomposite was successfully prepared in situ via the ion exchange and solvothermal process of a complex precursor of thiourea and Zn (CH3COO)2 at the molar ratio of 2∶1 at 170℃ for 4 h. XRD result shows that the d001 of kaolinite-montmorillonite (KM) is pillared to 1.95 nm from 0.98 nm, which is due to the accommodation of ZnS in the gallery of KM. SEM images illustrate that the uniformly distributed ZnS agglomeration exists on the partially exfoliated KM layers, and TEM verifies that the agglomerated ZnS (～25 nm) is stacked by ZnS subparticles (3～5 nm), which is intercalated in the layers of KM. SAED and EDS confirm that the particles are of hexagonal ZnS with low crystallization. Photo degradation of eosin-B was performed to test the catalytic activity of the prepared ZnS-PKM. UV-Vis absorption spectrum tracking the course of the degradation reaction shows that eosin-B is demineralized in 20min without the formation of new pollutant, and its activity is much higher than activities reported ZnS nanoparticles in references. The probable mechanism lies in the protection of ZnS nanoparticles by the layers of KM from agglomeration, which leads to the possibility of the reuse of ZnS-PKM.