At　present,　wear　models　and　accuracy　prediction　of　guideway　are　established　based　on　elastoplastic　mechanics　of　continuous　media.　These　methods　are　limited　to　describe　the　process　of　accuracy　degradation　by　using　the　material　performance　defined　based　on　macroscopic　hypothesis　condition.　In　this　paper,　the　multiscale　method　based　on　quasicontinuum　medium(QM)　principle　is　proposed　to　describe　the　degradation　process　of　guideway　linear　precision　with　an　exponential　model.　According　to　the　wear　distribution　of　the　guideway　surface　with　the　micro-morphology　evolution　process,　the　measurement　value　of　the　guideway　linear　precision　is　modeled　systematically.　Then,　using　the　quasicontinuum　medium　method　instead　of　the　continuum　hypothesis,　the　exponential　wear　model　of　guideway　is　established.　The　exponential　wear　model　uses　the　wear　exponent　to　describe　the　wear　status　based　on　linear　precision　measurement　rather　than　tremendous　wear　volume　tests.　By　means　of　Depth　From　Defocus　(DFD)　method,　the　micro-topography　information　of　the　guideway　surface　is　obtained.　Therefore,　the　wear　state　of　the　guideway　is　verified　under　different　loading　conditions,　and　the　validity　of　using　the　QM　method　to　establish　the　guideway　exponential　wear　model　is　verified.