探讨了利用缸盖振动信号诊断内燃机气阀漏气的一种新方法——小波包方法。诊断机理分析和实验研究表明 ,缸盖振动信号中关于气阀漏气的特征信息集中在高频段 ,故选用了小波包变换作为信号处理的基本方法 ,因为小波包变换较之小波变换在中高频段具有更高更均匀的频率分辨率 ;对实测信号的分析和处理结果表明了小波包在该领域的适用性 ;建立了基于马氏距离法的气阀漏气多指标诊断模型 ;进行了实机诊断 ,取得了预期的效果 A new method to diagnose the gas leakage of internal combustion engine valve by using vibration signal of cylinder head is discussed. The diagnosis mechanism analysis and experimental research show that the characteristic information of the valve leakage in the cylinder head vibration signals is concentrated in the high frequency band, so the wavelet packet transform is chosen as the basic method of signal processing. Because the wavelet packet transform is more effective than the wavelet transform in medium- The segment has a higher and more uniform frequency resolution; the analysis and processing results of the measured signal show the applicability of the wavelet packet in this field; established a multi-index diagnosis model of gas leakage based on Mahalanobis distance method; Machine diagnosis, achieved the desired results