Abstract: To improve the welding quality of circumferential welds of the titanium tube-sheet joint of power plant condenser, an automatic tube-sheet welding system with digital control and visual operation characteristics is developed. The main circuit of welding inverter adopted a frequency of 100 kHz fullbridge topology for improving the dynamic response performance. The digital control system for the welding process is designed based on ARM Cortex-M4,in which the LM4F232 MCU is used as the core element. The parameter self-tuning PI algorithm based on fuzzy logic judge is developed to improve the welding adaptability under different working conditions. The human-computer interactive system based on ARM microprocessor and touch screen is designed,achieving digitalization and visualization of human-computer interaction. System testing and welding experiments show that the developed tube sheet automatic welding machine is with good performance,and can meet the demands of high quality and efficiency welding for the condenser titanium tube sheet joints.