Abstract: This paper dcscribes the principle, the hardware interface circuits, the control programme and the programme parameters of the mirocomputer ontrol system for SR welding retifier. The realtime control on the dynamic and the statie characteristis of the rectifier has been analyzed and discussed to promote the development of mirocomputer-besed welders. The results of the electri and welding tests show that by using the microcomputer system, the SCR rectifier can provide a widely adjustable dynami behavio with a flexible are and little welding spatlers to satisly welding requirements.