The platinum-doped graphene has been achieved in our previous experiments. To further study the effects of metal doping on the band structures of graphene, and provide theoretical guidance for the next step of the experiment, we analyze the electronic properties of armchair graphene nanoribbons (AGNRs) with platinum atoms doping in the divacancy positions using first principle calculation based on density functional theory. The results show that the band structures of AGNRs can be effectively tailored by controlling the doping position on ribbons. Edge position is the most stable position for platinum atom. The band gaps of edge doped AGNRs can be shown in three curves like that of pristine AGNRs. However, they degenerate into two curves at large width, inhibiting the vibration of band gaps to some extent. In addition, several narrow platinum-doped AGNRs with width index Na = 3p and 3p + 1 have impurity level(s) in the band gap, reducing the large band gap effectively. Furthermore, band characteristics of platinum doped AGNRs are not sensitive to doping concentration, thus reducing the challenge of experimental precision. Our results will promote the application of graphene nanoribbons in the field of nano-electronics.