A　harmonic　analysis　method　based　on　ANF　(Adaptive　Notch　Filter)　is　proposed　to　improve　the　interference　suppression　of　dielectric　loss　angle　measurement.　ANF　can　effectively　filter　out　the　integer　harmonics,　inter-harmonics　and　noise　contained　in　the　voltage/current　waveform,　track　the　fundamental　component　and　accurately　extract　the　fundamental　frequency,　with　which,　the　dielectric　loss　angle　is　calculated　by　harmonic　analysis　method.　Simulative　result　indicates　that,　the　method　of　harmonic　analysis　based　on　ANF　has　higher　measurement　precision　in　the　conditions　of　frequency　fluctuation,　harmonic　component　variation,　white　noise,　dielectric　loss　angle　variation,　initial　phase　angel　variation　and　so　on.