Abstract: Voice activity detection,which is needed in speech codec,speech recognition and speech enhancement,is very important in speech processing.Conventional voice activity detection methods based on some simple features such as short term energy cannot meet the demand of application in noisy environment.Speech formants and pitches are used as the features to detect the voice activity in this paper.The information of the first formant and the pitch of speech signal are used to detect the starting points and end points of active voice.Experimental results show that this method can obtain higher accuracy than ordinary detection methods based on energy and the method proposed in AMR_WB standard.