Aiming　at　the　issue　of　measurement　accuracy　affected　by　hysteretic　PZT　deformation　in　absolute　distance　measurement　system,　by　tunable　external-cavity　diode　laser　frequency　scanned　interferometry,　a　modified　strategy　with　driving　laser　signal　waveform　of　partial　quadratic　curve　transition　in　time　domain　is　proposed.　By　least　square　peak　detection　of　interference　signal,　the　effect　of　tuning　nonlinearity　on　the　interference　signal　is　analyzed.　The　non-linear　system　output　is　compensated　by　analyzing　the　transfer　function　of　laser　control　system.　The　results　indicate　that　the　correction　of　driving　signal　effectively　improves　the　waveform　distortion　of　the　interference　signal,　and　the　measuring　accuracy　is　increased　tenfold　with　phase　measurement　and　compensation　for　linear　laser　output.