The currently prevalent machine performance degradation assessment techniques involve estimating a machine’s current condition based upon the recognition of indications of failure features,which entail complete data collected in different conditions.However,failure data are always hard to acquire,thus making those techniques hard to be applied.In this paper,a novel method which does not need failure history data is introduced.Wavelet packet decomposition(WPD) is used to extract features from raw signals,principal component analysis(PCA) is utilized to reduce feature dimensions,and Gaussian mixture model(GMM) is then applied to approximate the feature space distributions.Single-channel confidence value(SCV) is calculated by the overlap between GMM of the monitoring condition and that of the normal condition,which can indicate the performance of single-channel.Furthermore,multi-channel confidence value(MCV),which can be deemed as the overall performance index of multi-channel,is calculated via logistic regression(LR) and that the task of decision-level sensor fusion is also completed.Both SCV and MCV can serve as the basis on which proactive maintenance measures can be taken,thus preventing machine breakdown.The method has been adopted to assess the performance of the turbine of a centrifugal compressor in a factory of Petro-China,and the result shows that it can effectively complete this task.The proposed method has engineering significance for machine performance degradation assessment. The currently prevalent machine performance degradation assessment techniques assess a machine’s current condition based upon the recognition of indications of failure features, which entail complete data collected in different conditions. However, failure data are always hard to acquire, thus making those techniques hard to be applied.In this paper, a novel method which does not need failure history data is introduced. WPT is used to extract features from raw signals, principal component analysis (PCA) is utilized to reduce feature dimensions, and Gaussian mixture model (GMM) is then applied to approximate the feature space distributions. Single-channel confidence value (SCV) is calculated by the overlap between GMM of the monitoring condition and that of the normal condition, which can indicate the performance of single-channel. Moreover, multi-channel confidence value (MCV), which can be deemed as the overall performance index of multi-channel, is calculat ed via logistic regression (LR) and that the task of decision-level sensor fusion is also completed.Both SCV and MCV can serve as the basis on which proactive maintenance measures can be taken, thus preventing machine breakdown. The method has been adopted to assess the performance of the turbine of a centrifugal compressor in a factory of Petro-China, and the result shows that it can effectively complete this task. proposed method has engineering significance for machine performance degradation assessment.