The　performance　of　the　Cu2ZnSnS4　based　solar　cell　is　investigated　using　a　simulation　program　called　Solar　Cell　Capacitance　Simulator　(SCAPS).　The　cell　structure　is　based　on　Cu2ZnSnS4　(CZTS)　compound　semiconductor　as　the　absorber　layer,　n-doped　and　un-doped　(i)　zinc　oxide　as　the　window　layer,　In2S3　as　the　buffer　layer.We　study　the　influence　of　the　defect　density,　carrier　density,　thickness　of　the　CZTS　absorber　layer,　working　temperature,　In2S3　buffer　layer　thickness　and　its　carrier　density　on　the　cell　performance.　The　simulation　results　illustrate　that　the　optimal　layer　thickness　is　from　2500　to　3000　nm　for　the　absorber　layer,　and　that　in　the　range　of　20　to　30　nm　for　the　buffer　layer.　Besides,　controlling　the　CZTS　defect　density　under　1　×　1013　cm-3　is　very　necessary　for　high　efficiency　CZTS　cells.　The　increased　working　temperature　has　a　strong　influence　on　the　solar　cell　efficiency　and　the　temperature　coefficient　is　calculated　to　be　about　-0.17%/K.　An　optimal　photovoltaic　property　has　been　achieved　with　an　efficiency　of　19.28%　(with　Jsc　=　23.37　mA/cm2,　Voc　=　0.958　V　and　FF　=　86.13%).　All　these　simulation　results　will　give　some　important　guides　for　feasibly　fabricating　higher　efficiency　CZTS　solar　cells.