Switching power supply is a kind of power supply that maintains a stable output by using modern power electronic technology and controlling the opened and shut off time ratio. Switching power supply is generally made up by pulse width modulation (PWM) control IC and MOSFET. With the development and innovation of power electronic technology, switching power supply technology is also in constant innovation. Currently, switching power supply is widely used in almost all electronic devices because of the characteristics of small, lightweight and high efficiency. It is an integral part of power supply mode that made the electronic information industry rapidly develop today.