Defect engineering is recognized as an effective route to obtain highly active photocatalytic materials. However, the current understanding of defects is mainly limited to isolated atomic vacancy defects, ignoring the exploration of the functions of multivariate defects formed by the deletion of several adjacent atoms in photocatalytic system. Here, we prepared SnS₂ nanostructures with the same morphology but different dominant defects, and by testing their photocatalytic performance, it was found that the multivariate defects can significantly improve the photocatalytic performance than isolated S vacancies. Combining experiments and theoretical calculations, we confirmed that the promotion of multivariate defects, especially “S-Sn-S” vacancy associates, on the photocatalytic performance is reflected in many aspects, such as the regulation of the energy band structure, the improvement of the charge separation efficiency, and the promotion of the adsorption and activation of guest molecules. SnS₂ with “S-Sn-S” vacancy associates exhibits excellent photocatalytic water purification ability. Under the induction of “S-Sn-S” vacancy associates, phenol was thoroughly photocatalytically decomposed, further confirming its excellent functionality. This work not only provides new insights into identifying advantage defects in the catalyst structure, but also offers new ideas for constructing highly active photocatalysts based on defect engineering.