Copper Zinc Tin Sulfide (CZTS) solar cells have recently attracted attention as a potential low-cost earth abundant replacement for CIGS cells. This is due to their constituent’s Zn and Sn are non-toxic and earth-abundant compare to the elements of In and Ga in CIGS. Thus, aiming to analyse solar cells free from the environmental contaminant, CZTS is viewed as a potential candidate as the absorber for the next generation thin film solar cells. However, the conversion efficiency of CZTS based solar cells reported which is relatively low (highest conversion efficiency recorded is 12.5%) from the theoretical conversion efficiency limit of 32.2%. This is due to the low fill factor (FF), open circuit voltage (Voc) and current density (Jsc). In this study analysis of the different CZTS based solar cells and its synthesis methods will be reviewed. The effect of the compositional change and various structure in the CZTS, different buffer layers with their interfaces are thoroughly studied. The challenges regarding improving the conversion efficiency of CZTS solar cells and their future in the thin film solar cell application are discussed.