Abstract: To resolve the problem of quantitative analysis on classificatory information systems, a quantitative analysis technique is proposed based on security entropy. Firstly, the security entropy is put forward according to the information theory, to calculate the uncertainty of the system's determinations on the
irregular access behaviors. Then the security theorems of classificatory information systems are defined based on security entropy. Finally, the typical access control models are analyzed by the technique, the technique's practicability is validated, and security and applicability of these models are compared. The result proves that the technique is suit for security quantitative analysis on access control model and evaluation to access control capability in information system

Key words: information entropy, security entropy, classificatory access control model, directly unauthorized access, right about access