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. <EOS>