In this work, the performance of solar cell based on CdS-n/Cu2ZnSnS4-p hetero-junction is numerically simulated. The aim of the study is to investigate the influence of thickness, defects density and bandgap energy of absorber layer CZTS and the thickness of the buffer layer CdS of the solar cell on electrical parameters J(sc), V-oc, FF and efficiency eta of the cell. The results of our simulation allowed us to optimize the parameters above mentioned in order to get the best efficiency at the optimal band gap which corresponds to the maximum of the solar spectrum with optimal values of the electrical performances of the cell. This results lead to develop CZTS solar cells with high efficiency and low cost and give a help full indication for fabrication process. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.