The　main　factor　affecting　the　optical　fiber　spatial　resolution　of　OFDR　system　is　the　non-linearity　of　laser　frequency　tuning.We　demonstrated　a　M-Z　interferometry　and　performed　nonlinear　measurements　at　different　frequencies.　The　main　and　auxiliary　interferometers　with　tunable　laser　source(TLS)　were　built,　and　the　auxiliary　interferometer　was　used　to　correct　the　nonlinearity　modulation　of　the　frequecny　of　the　main　laser.The　interpolation　compensation　scheme　was　proposed.The　research　results　of　the　nonlinear　frequency　modulation　of　TLS　to　improve　the　spatial　resolution　of　optical　fiber　vibration　sensing　was　demonstrated,the　spatial　resolution　is　0.17m.