In order to further reveal the whole diffusion characters and distribution behaviors of Ga impurity in SiO2/Si system, the changeable concentration laws of Ga impurity at puny region of the nearby Si surface, under different temperatures and different atmosphere in invariable resource diffusion, finite resource diffusion and re-oxygenation process are investigated by SRP. The results are as follows: the low concentration region forms in invariable resource diffusion process; the reversed diffusion character happens in finite resource diffusion process; the exceptional segregation comes into being in re-oxygenation process.