This paper studied the time-domain waveform characteristics of diesel engine cylinder head vibration. The relative relationship between the various explosions of diesel engine were analyzed and compared. Seven criteria were proposed under which to achieve the time domain waveform peak identification in the absence of TDC signal. According to the criteria computer algorithms for the time domain waveform peak identification were given. The method can reduce the vibration diagnosis system using request such as can achieve misfire fault diagnosis in the absence of TDC signal.