A nitride semiconductor transistor, comprising a substrate structure, a nitride epitaxial structure, and a functional electrode layer, wherein the substrate structure comprises a heavily doped P-type substrate and a lightly doped P-type epitaxial layer that are disposed through stacking, and an N-type region extending from a side that is of the lightly doped P-type epitaxial layer and that is away from the heavily doped P-type substrate towards the heavily doped P-type substrate; the nitride epitaxial structure comprises a nitride buffer layer, a barrier layer, and a P-type nitride layer that are successively formed on the lightly doped P-type epitaxial layer; the functional electrode layer comprises a source, a drain, a gate, and an isolation layer, the source and the drain are disposed on the barrier layer, the gate is disposed on the P-type nitride layer, and the isolation layer covers the source, the gate, the barrier layer, and the P-type nitride layer; and the drain separates the isolation layer into a first isolation portion and a second isolation portion, the first isolation portion penetrates through the barrier layer and the nitride buffer layer to be in contact with the lightly doped P-type epitaxial layer and the N-type region, a metal connector is formed in the first isolation portion, and the metal connector penetrates through the first isolation portion to connect the drain and the N-type region, wherein a protection ring combination surrounding the N-type region is formed on the lightly doped P-type epitaxial layer, and wherein the protection ring combination comprises at least one protection ring and said at least one protection ring is N-type. the substrate structure comprises a heavily doped P-type substrate and a lightly doped P-type epitaxial layer that are disposed through stacking, and an N-type region extending from a side that is of the lightly doped P-type epitaxial layer and that is away from the heavily doped P-type substrate towards the heavily doped P-type substrate; the nitride epitaxial structure comprises a nitride buffer layer, a barrier layer, and a P-type nitride layer that are successively formed on the lightly doped P-type epitaxial layer; the functional electrode layer comprises a source, a drain, a gate, and an isolation layer, the source and the drain are disposed on the barrier layer, the gate is disposed on the P-type nitride layer, and the isolation layer covers the source, the gate, the barrier layer, and the P-type nitride layer; and the drain separates the isolation layer into a first isolation portion and a second isolation portion, the first isolation portion penetrates through the barrier layer and the nitride buffer layer to be in contact with the lightly doped P-type epitaxial layer and the N-type region, a metal connector is formed in the first isolation portion, and the metal connector penetrates through the first isolation portion to connect the drain and the N-type region, wherein a protection ring combination surrounding the N-type region is formed on the lightly doped P-type epitaxial layer, and wherein the protection ring combination comprises at least one protection ring and said at least one protection ring is N-type.