Based　on　the　analysis　of　the　principle　and　flame　movement　of　a　pipe　cutting　machine　tool,　a　retrofit　NC　flame　pipe　cutting　machine　tool　(NFPCM)　that　can　meet　the　demands　of　cutting　various　pipes　is　proposed.　The　paper　deals　with　the　design　and　implementation　of　an　open　architecture　CNC　system　for　the　NFPCM,　many　of　whose　aspects　are　similar　to　milling　machines;　however,　different　from　their　machining　processes　and　control　strategies.　The　paper　emphasizes　on　the　NC　system　structure　and　the　method　for　directly　creating　the　NC　file　according　to　the　cutting　type　and　parameters.　Further,　the　paper　develops　the　program　and　sets　up　the　open　and　module　NC　system.　©　2009　Higher　Education　Press　and　Springer-Verlag　GmbH.