In this present study Cu2ZnSnS4 (CZTS) thin films were grown by Chemical Bath Deposition (CBD) method at optimized parameters. These as grown CZTS films were annealed at 3000C for different time 1 hr, 2 hr, 3 hr. These films were characterized by scanning electron microscope (SEM), UV-VIS Spectrophotometer, I-V measurement for study of surface morphology, optical and electrical properties respectively. The SEM analysis revealed that surface modification takes place as the annealing time increases. The optical study shows high absorption in visible region and as annealing time increase red shift in energy band gap occurred. The current-voltage characteristics of the specimen indicated that conductivity of film increases with increased annealing time. Thus, annealing time has prominent impact on surface modification which changes optoelectronic properties of CZTS thin film and results shows that film annealed at 3000C for 3 hr gives high absorption and better conductivity for CZTS thin films. Copyright © 2018 VBRI Press.