The manufacturing method of oxide thin film transistors (TFTs) includes: providing a substrate and forming an oxide semiconductor active layer on the substrate; depositing an insulation dielectric layer on the active layer; and applying an annealing process to components formed after the insulation dielectric layer is deposited. After depositing the gate insulation layer on the oxide semiconductor active layer, the annealing process is applied to the formed component, which eliminates the difference of the component performance caused by the insulation dielectric layer formed by different film formation processes such that the reproducibility of the film formation processes may be enhanced.