The invention discloses a device structure of a metallic oxide field effect transistor and a manufacturing method thereof. The device structure comprises a substrate (1), a Ga2O3 epitaxial layer (2) and low-doped n-type Ga2O3 thin film (3) from bottom to top, the thin film is provided with a high-doped n-type ion-implanted region (4) and an insulated gate medium (7), the ion-implanted region is provided with a source electrode (5) and a drain electrode (6), the insulated gate medium is provided with a gate electrode (8), the Ga2O3 epitaxial layer is provided with multiple hydrogen-ion-implanted regions (9), the hydrogen-ion-implanted regions are located in the epitaxial layer between the gate electrode and the drain electrode, and meanwhile with the distance increase of the hydrogen-ion-implanted regions and the gate electrode, the widths of the hydrogen-ion-implanted regions are reduced, and intervals among the hydrogen-ion-implanted regions are increased. According to the device structure of the metallic oxide field effect transistor and the manufacturing method thereof, an electric field is adjusted through attraction of hydrogen ions to electrons, a breakdown voltage of a device is improved, and the device structure can be used as a power device and a high voltage switch device.