CZTS thin-film is now one of the most promising materials for the sustainable absorption of solar cells. Recently, there has been interest in enhancing efficiency and reducing costs of manufacturing CZTS-based solar cells. Nevertheless, there is no report focused on explaining the role of numerical modeling’s help to understand this cell. In this review, we discuss the advantages and the challenges of the experimental pure sulfide CZTS-based solar cells. The softwares used in simulations thin-films solar cells are discussed. The solutions for improving efficiency of CdS/CZTS-based solar cells using numerical modeling are also discussed.