A　new　time-frequency　analysis　method　based　on　wavelet　packet　transform　in　allusion　to　time-varying　harmonic　measurement　is　presented.　According　to　the　power　complementary　of　conjugate　quadrature　filter　bank,　the　time-varying　harmonic　signal　is　decomposed　with　same　resolution　in　frequency-domain　by　wavelet　packet　transform.　Then　the　outputs　of　all　subbands　are　cross-combined　and　that　make　different　levels　of　harmonics　fall　on　their　corresponding　frequency　bands.　So,　the　time-varying　harmonics　could　be　detected　and　the　time-frequency　analysis　would　be　realized.