A synchronous rectifier circuit for AC-DC power adaptor was designed, which integrated synchronous rectifier control chips, power MOSFETs and energy storage capacitors. The new rectifier circuit could quickly and accurately switch the power MOSFET without external power supply, external drive signal and external components. So the synchronous rectification function was realized. Compared with the traditional Schottky rectifier circuits, this rectifier circuit had higher efficiency, fewer peripheral devices and wider application range. The synchronous rectifier chip was designed and realized in a 0.35 μm high voltage CMOS process. The results showed that the measured average efficiency of the rectifier circuit was 3% higher than that of the traditional circuit under the AC input voltage of 220 V, the output voltage of 5 V and the maximum load current of 5 A.