Based on the comprehensive analysis of welding circuit for CO2 arc power, a system model through power, cable, wire, molten droplet and arc,was created, and according to distributed temperature function about a variable of genuine length of wire, a wire-voltage function was developed. Then, a dynamic and multicycle molten droplet- voltage mathematic model was also found by the time weight coefficient for the equivalent length of short-circuit transferring molten droplet and by the transform of wire volume from a solid to a liquid state. Besides these, a arc-voltage function involving the welding current, the genuine length of wire and the height of welding torch, was established logically and especially. Meanwhile, the correlative parameters were simultaneously analyzed. At last, the acute comparison was made between simulation and experimental oscillograms of voltage and current herein.
