Abstract: The author’s opinion is advanced about the meaning of the functional occlusal contact area, and then a new method is proposed tn measure occlusal contact area in complete denture by IBAS 2000 （Interactive Image Analysis System）. 16 cases are analyed in this article. The result indicates that a given occlusal contact area is basic to mastication; different parts of the occlusal area function different in mastication, so we should handle it differently.