CASE tools based on EERD modeling are major applicated on development of database application. These tools could improve the efficiency and accuracy of the developing database application greatly. This paper particularly describes the basic architecture and function of CASE tools in this field as well as the implement technology, and presents the whole structure of the concept data model of the data dictionary included by CASE tools through the analyse of sorts of CASE tools in prevalence, and also illustrate the relationship of model elements which compose the concept data model.