Because　of　the　problems　of　fault　diagnosis　in　the　power　electric　circuit　and　the　merit　of　FCM　is　efficient　in　clustering　and　the　merit　of　hidden　Markov　model　(HMM)　that　have　the　ability　to　deal　with　continuous　dynamic　signals　and　the　merit　of　support　vector　machine　(SVM)　with　perfect　classifying　ability,　FCM-HMM-SVM　based　diagnosing　method　is　presented.　With　the　features　extracted　from　the　circuit　,　based　on　the　trained　FCM　algorithm,　HMM　was　used　to　calculate　the　matching　degree　among　the　unknown　signal　and　the　circuit＇s　states　,　which　formed　the　features　for　SVM　to　diagnosis.The　experimental　results　show　that　the　proposed　method　has　a　high　correct　rate.　©2010　IEEE.