This　paper　focused　on　the　grinding　accuracy　of　an　automotive　camshaft　and　executed　related　research　in　order　to　improve　the　geometric　accuracy　of　MKS8332A　CNC　camshaft　grinder　and　improved　the　camshaft　grinding　accuracy　and　processing　efficiency.　A　geometric　error　model　of　this　grinder　was　analyzed　and　established　by　the　utilization　of　multi-body　system　theory,　and　the　motion　constraint　equation　of　precision　machining　was　given.　Combining　the　geometric　error　parameter　identification　model　based　on　multi-body　system　theory　with　a　double　ball　bar　the　identification　methods　were　put　forward　and　could　identify　the　geometric　error　parameters　of　the　grinder　well.　On　the　basis　of　above,　the　calculation　methods　for　precision　NC　instructions　and　inverse　contour　of　cam,　ideal　NC　instructions,　grinding　errors　were　all　discussed　in　detail.　At　last,　a　fitting　method　of　the　cam-shaped　curve　and　the　calculation　method　of　the　tool　path　were　all　given.