Based on the theory of expert systems, simulating thoughts process of experts, gathering domain knowledge of all experts and according to the problem characteristics of application and management system, an expert systems model of malfunction intelligent diagnose has been built up. In the system, the method of knowledge representation is genetic rule, the inference engine combines uncertain inference and rule inference. In order to deal with the uncertain knowledge, an uncertain inference model based on confirmation theory is established. This model can auto-gets and modify knowledge in knowledge base, achieve a better real-time characteristics, through interacting between human and machine as well as self-learning function.