Abstract: In view of the problem that the current ultrasonic processing device is usually operated at a single frequency and used for a special purpose, a new type of broadband ultrasonic power supply system based on System-On-a-Pro- grammable-Chip(SOPC) is proposed. With the advantage of the field programmable gate array (FPGA) in programming logic and math operations, this system transplants Nios II soft core as main controller and PS-PWM for adjusting frequency and power, and uses the orthogonal circuit for detecting the phase difference between output voltage and current. The experimental results show that the proposed scheme can make the ultrasonic oscillator working at an approximate resonant state in a specified frequency band of 20~40 kHz.