The　machining　precision　of　grinding　machine　determines　the　precision　of　parts.　To　improve　the　machining　accuracy,　an　effective　geometric　error　modeling　and　compensation　method　was　proposed.　Firstly,　the　comprehensive　error　model　of　grinding　machine　was　established　based　on　differential　theory.　In　contrast　to　the　multi-body　system　theory,　the　proposed　modeling　method　can　simplify　the　calculation　process　and　reflect　the　influence　of　each　component　on　the　tool.　Secondly,　MATLAB　curve　fitting　tool　was　used　to　fit　the　known　error　function,　and　a　link　between　24　basic　geometric　error　terms　(BGETs)　and　milling　instructions　was　discovered　using　the　sum　of　sine　function.　Finally,　the　compensation　dosage　(dx　dz　db　dc)　for　the　grinding　machine　comprehensive　error　was　determined　by　combining　24　fitting　functions,　the　known　error,　the　differential　matrix　of　each　part,　and　the　Jacobian　matrix.　To　test　the　feasibility　of　the　above　method,　the　grinding　machine　geometric　error　compensation　experiment　was　conducted.　The　average　machining　accuracy　is　increased　by　15.948%.　It　is　showed　that　the　proposed　method　can　realize　the　error　compensation　of　CNC　grinding　machine　well.