Abstract: A digital control system with TMS320LF2407A DSP as its kernel was designed aiming at some deficiencies in the simulating control system and single-chip control system, such as poor flexibility, control precision and reliability.The hardware circuit and software flow chart were presented.In this control system, fuzzy control and close-loop control were applied to control the arc length, and modification mechanism of PFM to modify the pulse shape.The experimental results show that the pulse MIG welding digital control system based on DSP has the advantages of quicker response, better reliability, more stable arc length and better-formed welding seam, over the traditional simulating control system and single-chip control system;furthermore, by using the fuzzy control theory, the stability of welding process is improved and the optimization of multi-parameters match is solved.