Abstract: Investigate 802 students from the first grade students to the third grade students in 6 schools in Beijing by measuring method and study the development levels of Function concept of junior high school students.The results show that the development of Function concept has special age factor and teaching contents evidently influence the development levels of Function concept.The dialectic thinking ability for the relation between negative and positive is weaker for junior high school students,in addition,near 50 per cent students can not think by view of movement and variation.The second-grade in junior high school is a key stage for the development of Function concept.Since the second grade,the ability of processing word and graphics information remarkably increase but the ability of transition between word information and graphics information is weaker.When studying the relation of the same kind of things,they can not generally understand the relation between the abstract and amount without concrete content.

Key words: junior high school students, Function concept, development