Shield gate power transistor and preparation method thereof

The embodiment of the invention provides a shield gate power transistor and a preparation method thereof. The shield gate power transistor comprises a first conductive type substrate and a first conductive type epitaxial layer stacked on the first conductive type substrate, wherein a cellular region and a terminal region are arranged in the first conductive type epitaxial layer; a first groove surrounding the cellular region is arranged in the terminal region, a first gate structure is arranged in the first groove, the first gate structure starting end of the first gate structure is close to the cellular region, the first gate structure tail end is far away from the cellular region, and the potential connected with the first gate structure starting end is lower than the potential connected with the first gate structure tail end. The first trench in the terminal region and the first gate structure surround and extend together to surround the cellular region. The tail end turn-on potential of the first gate str