As　a　technology　of　context　analysis,　the　detective　method　of　polyphonic　sound　event　detection　has　a　widespread　prospect　of　application.　In　this　paper,　a　detective　method　of　polyphonic　sound　event　were　proposed　to　resolve　the　challenge　in　IEEE　DCASE2017　task　3　based　on　full　convolutional　DenseNet.　Relevant　results　illustrated　that　the　method　is　higher　in　F-score　and　lower　in　ER　than　the　baseline　method　proposed　by　IEEE　DCASE2017　based　on　DNNs,　and　also　get　higher　performance-7.4%　higher　in　F-score　and　3%　lower　in　ER　than　the　best　method　in　IEEE　DCASE2017　challenge　based　on　CRNN.　©　2018　IEEE.