Abstract: Disclosed are a GaN power device and a manufacturing method thereof. The GaN power device includes a substrate, and a buffer layer, a GaN channel layer and a barrier layer sequentially stacked on the substrate from bottom to top. The barrier layer is provided with a p-GaN cap layer and a p-GaN thin layer, and the p-GaN thin layer is configured to cover the surface of the barrier layer and is connected to the p-GaN cap layer; the upper surface of the barrier layer is also provided with an input electrode and an output electrode, and a control electrode is provided on the upper surface of the p-GaN cap layer. The control electrode and the p-GaN thin layer are located between the input electrode and the output electrode.