A batch of TiO ₂films with different Zn ²⁺compositions were prepared on a single crystal silicon substrate using sol-gel method to observe the changes in optical and photocatalytic properties during the alloying process of Zn ²⁺and TiO ₂. XRD was used to observe the changes in the crystal structure of the films during the alloying process and to track the formation of ZnTiO ₃compounds. SEM and AFM were used to observe the phenomenon of large number of holes on the surface of the films due to the limited solubility of the crystal lattice for Zn ²⁺during the alloying process. XPS and optical bandgap were used to observe the changes at the level of the electronic structure of the films during the alloying process of Zn ²⁺with TiO ₂. Finally, by degrading the MB solution, it is shown that a small amount of Zn ²⁺doping is completely dissolved in TiO ₂and destroys the TiO ₂crystalline quality. As the compositional share of Zn ²⁺continues to increase to 15%, the limited solubility of TiO ₂for Zn ²⁺is verified in the XPS peak fitting, resulting in a large number of hole structures in the film, and the active specific surface area of the film is enhanced, while Zn ²⁺effectively traps the photogenerated e ^-/h ⁺. In order to continue to observe the effect of Zn ²⁺concentration on TiO ₂, we increased the concentration of Zn ²⁺to 40% and observed the phenomenon during the alloying process of Zn ²⁺with TiO ₂. It is shown that the appearance of the compound ZnTiO ₃can act as a complex centre for e ^-/h ⁺as well as a significant decrease in the percentage of TiO ₂leads to a gradual decrease in the photocatalytic efficiency of the films after alloying.