Abstract: In order to meet the requirements of the miniaturization of electronic devices for the fine control of welding energy, a high-frequency inverter type micro-resistance seam welding power source was designed. The insulated gate bipolar transistor IGBT module was used to build the high-frequency inverter circuit, and the inverter frequency reached 10 kHz, shortened the energy output regulation time, improved the pulse output frequency. To improve the computing capability of the system, a fully digital control system based on dual MCU architecture was designed to achieve digital control of PWM (Pulse width modulation) and the output energy waveform. In this paper, the load characteristics of the power supply were analyzed, and a five-stage output waveform scheme was designed for the phenomena of shunt and over-melting in the welding, and the output control modes of constant current, constant voltage and constant power were proposed, and the fuzzy adaptive PID intelligent control algorithm was used to realize the stable output of multi-stage pulse energy. The results showed that the intelligent control algorithm could effectively control the welding output energy, with good stability. Through the precise control of current, time, pulse number and other parameters, accurate control of output energy and waveform could be achieved, while beautiful, dense fish scale pattern weld was obtained with no obvious defects.