The　precision　of　Frequency-scanning　interferometer(FSI)　for　absolute　distance　measurement　depends　much　on　the　tunability　of　its　laser　source.　However,　an　external　cavity　laser　diode　(ECLD)　exhibits　nonlinearity　during　optical　frequency　sweep　due　to　hysteresis　inherent　to　the　piezoelectric　ceramic　transducer　(PZT)　actuator　in　the　ECDL.　As　a　result,　the　interference　signal　become　nonstationary,　and　then　extracting　the　phase　of　the　nonstationary　interference　signal　may　cause　errors.　To　address　this　problem,　we　propose　a　new　method　based　on　the　Prandtl-Ishlinskii　(PI)　model　for　suppressing　nonlinearity　of　optical　frequency　sweeping.　For　the　proposed　FSI,　the　output　transmission　signal　of　a　Fabry-Perot　(F-P)　cavity　is　used　to　obtain　the　optical　frequency　curve　of　the　ECLD.　By　using　the　input　voltage　of　the　linear　driving　signal　and　the　optical　frequency　of　the　ECLD　as　input　and　output　of　the　model　respectively,　the　hysteresis　model　can　be　built　based　on　PI　modelling　method.　Hence,　the　inverse　of　the　rate-independent　PI　model　is　employed　as　a　feedforward　controller　to　compensate　the　nonlinearity　of　the　optical　frequency　sweeping.　In　our　case,　instead　of　driving　the　ECLD　with　a　linear　signal,　we　implement　a　corrected　nonlinear　driving　signal　of　the　PZT　to　suppress　the　nonlinearity　of　the　sweeping　frequency.　Experimental　results　demonstrate　the　effectiveness　of　our　proposed　method.　Compared　with　an　external　witness　He-Ne　incremental　interferometer,　the　proposed　method　greatly　improves　the　performance　of　the　FSI　for　absolute　distance　measurement.