Machine　tools　usually　cut　two　or　more　surfaces　after　the　work　piece　clamped　on　work　table.　In　order　to　improve　the　machining　accuracy　and　optimize　accuracy　design,　it　is　hoped　that　the　geometric　errors　that　influence　the　accuracy　of　machined　surface　prominently　can　be　known　beforehand,　so　the　adjustment　will　be　carried　out　with　a　definite　objective　rather　than　without　any　clue.　Because　the　machining　accuracy　of　each　direction　in　3-D　space　is　different　value,　in　this　paper,　machining　accuracy　failure　mode　was　defined　as　the　various　combination　of　the　machining　accuracy　of　each　direction　according　to　whether　it　is　up　to　the　reserved　objective　value　or　not.　A　three-axis　machine　tool　was　selected　as　an　example　and　there　were　7　machining　accuracy　failure　modes　for　it.　Based　on　the　generalized　correlation　analysis,　the　correlation　relationships　between　7　machining　accuracyfailure　modes　were　analyzed,　and　the　main　failure　modes　that　affect　the　machining　accuracy　of　work　piece　to　be　machined　were　identified.　For　each　machining　accuracy　failure　mode,　key　geometric　error　that　had　major　influence　on　it　was　identified　based　on　sensitivity　analysis.　Finally,　four　stepped　work　pieces　were　milled　by　a　3-axis　machine　tool　to　illustrate　the　analytical　method　proposed　in　this　study.