Abstract This paper used rule space model to diagnose the students' cognitive situation, and changed that the test was only a test of scores, and expanded the diagnostic function of education evaluation. Taking "expression of material composition" in junior high school chemistry for example, this paper prepared test items for attributes to be examined, classified all test-takers as different response patterns from their actual response using rule space model, in order to analyze the cognitive state of students, diagnose the students' cognitive defects, and provide suggestions for teachers.
