GaN-based materials have bright market prospects in the field of high-temperature, high-speed and high-power applications owing to their superior physical properties. GaN-based power devices on Si substrate are current mainstream techniques, in which p-gate and cascade structure have been applied in industrial productions such as universal power supply and PV inverter. In view of the disadvantages of the above two kinds of device structure, high-performance true normally-off MOSFET is still recognized as the direction and goal in the industry. GaN MOSFET devices still face many technical bottlenecks and challenges in terms of materials epitaxy and device stability.