The　positioning　accuracy　of　CNC　machine　tool　is　the　best　moving　position　accuracy　which　the　machine　tool　can　reach　under　the　control　of　CNC　control　system.　The　principles　of　frequency　laser　interferometer　measurement　are　described　in　this　paper,　and　pitch　error　is　compensated　by　taking　DAHE　V1500　CNC　machine　with　FANUC　system　as　example.　The　result　shows　that　the　precision　of　CNC　machine　tool　is　effectively　improved.　©　(2014)　Trans　Tech　Publications,　Switzerland.