Clinical Decision Support System (CDSS) is a part of hospital informatization, the paper proposes a CDSS for the coronary heart disease based on Electronic Medical Records(EMR). It designs the system structure and functions, including the front-end display, database module and server function module, and introduces the work flow of the system. This system can return cured cases highly similar to cases to be treated. It will help doctors to realize individualized treatment and promote the development of clinical pathways.