The invention discloses a GaN-based fin gate enhanced device and a making method thereof mainly in order to solve the problem that the positive drift of threshold voltage of the existing similar device is small. The making process comprises the following steps: (1) making source and drain electrodes on a GaN buffer layer of an existing epitaxial plate; (2) etching an active region to form electrical isolation; (3) etching the active region between the source and the drain to form nanowire channels; (4) growing a SiN passivation layer on an AlGaN barrier layer, and photo-etching and etching a gate region to form a groove; (5) oxidizing the AlGaN barrier layer in the groove with oxygen ions through an ICP process, and making a gate electrode; (6) growing a SiN protective layer outside a groove gate electrode and the gate region, and photo-etching and etching the SiN protective layer to form a metal interconnection perforation region; and (7) making a metal interconnection layer on the interconnected perforated and non-perforated protective layer, thus completing the making of the device. The threshold voltage of the device is increased, and the enhanced effect is improved. The GaN-based fin gate enhanced device can be used in an enhanced/depleted digital integrated circuit.