时变退化在实际工程现场具有较强的普遍性，会给设备故障特征的提取和诊断带来困难。建立了一类具有时变退化率的烟气轮机性能退化模型，并研究了如何求解退化过程首达失效阈值时间的概率分布问题。实验仿真结果表明，新模型应用于烟气轮机故障的特征提取是有效的。“,”The time varying degradation is a very common phenomenon in practical industrial fields ,in which it is difficult to extract fault features and diagnose fault for equipment .Reduction model with time varying degradation rate is presented for rotating machinery in this pa-per .The paper also studies the probability distribution of time when the rotating machinery reaches its failure threshold in degenerative pro-cess .The simulation results show that the new model can effectively extract the features from the fault of the flue gas turbine .