Abstract: Addressing the air-planed bevel quality problem and welding quality problem of weld pipes and weld fittings as affected by the manual carbon-arc-air planning root-cleaning process, the submerged arc welding machine is modified into an automatic carbon-arc-air planer based on the power-supply arc voltage feedback principle of the submerged arc welding process, and combining the air-planning experimental research.The principle and characteristics of the carbonarc-air planning process are analyzed, and the principle and structure design of the company's self-made automatic carbonarc-air planer are detailed as a focus.Moreover the major process parameters of the carbon-arc-air planning process are briefed.The said self-made planer is in possession of such advantages as simplified structure, easy operation, high efficiency and low costs, etc., having been capable of solving the problems of root-cleaning concerning both the circular weld seam and the longitudinal weld seam, and having dimensionally-even and surface-smoothed planed groove.