With the development of hospital information construction, the focus has gradually changed from functions of the information system to data utilization. The utilization of medical data has great significance in health management, disease analysis, summary of treatment experience, and development of new technologies. By data mining technology, the paper extracts data related to the author's hospital, starts from intelligent diagnosis and simulates the establishment of the knowledge base for hospital clinical diagnosis. Upon verification, the relevance judged by the system is basically consistent with the clinical practice. Thus, it proposes the possibility to extend the application to hospital clinical pathways.