Apply　the　theory　of　multi-body　system,　this　paper　establishes　the　follow-up　error　analysis　model　of　grinding　machine,　and　focuses　on　the　study　of　its　error　identification　method　to　improve　the　accuracy　of　the　eccentric　shaft　servo　grinder,　providing　a　theoretical　basis　for　error　compensation　of　CNC　grinding　machine.　And　by　using　nine-line　identification　method　to　identify　the　all　21　items　of　geometric　errors　grinding　machine　translation　system　three　translational　axis　of,　By　using　the　nine　line　identification　method　of　the　translation　system　to　identify　the　all　21　items　of　geometric　errors　about　the　three　translational　axis　of　the　grinding　machine.　Based　on　the　three　indicators,　axial　runout,　radial　runout　and　totating　error　of　the　rotating　shaft,　to　arrive　at　the　basic　geometric　error　in　the　direction　of　six　degrees　of　freedom　of　the　rotating　shaft.　Motion　model　of　multibody　system　error　is　analyzed,　and　based　on　the　traditional　geometry　description　method　of　multibody　system,　putting　forward　more　practical　description　method　on　engineering　body　motion.　The　ideal　movement　of　engineering　object　and　the　motion　model　under　the　condition　of　error　are　reasonably　integrated　and　analyzed.　©　Published　under　licence　by　IOP　Publishing　Ltd.