The effects of annealing temperature and time on sol-gel Cu2ZnSnS4 thin film spin coated on soda lime glass substrate were investigated in terms of crystallinity, morphology, composition, optical and electrical properties. The annealing process was achieved in a tube furnace under N-2 gas flow and S vapor. The importance of this work is the detailed investigation of annealing temperature and its effect on the Cu2ZnSnS4 thin films that were prepared by the sol-gel spin coating method. The threshold temperature where the film begins to crystallize has been determined to be 465 degrees C. A temperature increase of 15 degrees C from 450 to 465 degrees C boosted the crystallite size and main peak intensities and optimized energy gap from 1.38 to 1.46 eV. In summary, the effect of the annealing temperature on the crystallinity of the films was studied in detail and the threshold temperature value which improved the crystallinity was determined.