Double metal saw blade has features of high cutting precision,low material loss and high work efficiency. In the field of metal cutting,its application in the metal cutting field is increasingly widespread and the market demand is also growing. For the welding of the double metal saw blade,a precision welding power source is developed. This welding power source takes the 32 bit microcontroller STM32F103RCT6 as the main control core,its IGBT control signals are generated by STM32 internal pulse modulation module through the drive circuit,and it uses sampling circuit and incremental PI algorithm to realize the accurate control of power output. The topological structure of main power circuit,the working principle and the hardware and software design of this precision welding power source for double metal saw blade are introduced in details. The results show that the welding power source is reasonable and reliable,has fast output dynamic response speed,adjustable frequency and excellent constant-current control effect.