Abstract: The problem of time distribution of multitask control system in digital TIG welding machine is solved by using two-CPU system of TMS320F240 digital signal processor and AT89C2051 single-chip controller.The main points of this two-CPU control system are the of tasks distribution to two CPUs,velocity matching of tasks and efficient communication between two CPUs.Communication model of this two-CPU system is analyzed in this paper.The software agreement of asynchronous communication suitable to the occasion of control system in welding machine is come up.The paper comes up with multitask control system from almost every aspects according to author's research on digital TIG welding machine,analyzes the principles of software and hardware,points out the superiority of this real-time control system centered by DSP (Digital Signal Processor) for the implementation of digitalization and information welding machine.