Objective:To put forward the concept of medical demand intensity(MDI) and to establish its measurement on the base of case mixed index(CMI) and all kinds of measurement of medical illness severity, it will help examine to which extent the health resources are needed by disease. Methods: All the cases of in-patients in 1996 in 3 hospitals were collected to caculate medical demand intensity index(MDII). Results: The current classification of hospital categories and ranks doesn′t suit the MDI degree and the efficiency of health resources. Conclusion: The resource allocation of health service should be based on the MDI， which gives the scientific basis for the reasonable proportion and structure of resource allocation in different type of hospitals， and also make it possible for efficient examination in hospitals.