We measured R-T characterization of various Sn granular film samples at low temperatures. The samples were prepared by using thermovaporization method in a vacuum chamber containing oxygen.Because of the grains and the grain sizes and the distance between the grains are randomly distributed, the Josephson coupling and the thermal excited electrons of hopping process between the grains are not identical for different samples. So the experimental results may be recognized as the following three kinds of processes: (1) transition to zero resistance; (2) minimum resistance; (3) metal-insulator transition.