文中介绍了旋转机械故障诊断知识常用的框架和规则表示方法以及专家系统中常用的不精确推理，深入论述了规则的结构、功能和类型，讨论了不精确推理在实际应用中存在的问题，结合规则表示方法对不精确推理算法进行了改进，提高了故障诊断的能力。 This paper introduces the commonly used frame and rule representation methods of rotating machinery fault diagnosis knowledge and inaccurate reasoning commonly used in expert systems. The structure, function and type of rules are discussed in depth, and the problems existing in practical application are discussed. The rule representation method improves the inaccurate reasoning algorithm and improves the ability of fault diagnosis.