Consumer health information is receiving more attention than ever before. This growing attention can be linked to the Internet and to people seeking more information on health topics. The purpose of this study is to suggest a design of the Knowledge management system for medical information services in a public library. As theoretical backgrounds, it discusses the issues regarding to the medical information services in a public library, knowledge management and knowledge management system. After that, 12 medical information sites are analyzed then the planning and the main menu of a medical information site for a public library are described. Finally, the model of the knowledge management system for a public library with 5 sub-systems are suggested: 1) knowledge creation system, 2) technology support system, 3) training system, 4) community service system, 5) knowledge sharing and network system. This system based on knowledge management will help provide the users high quality of medical information.