Abstract: STEP is the standard for product data representation and exchange which is being developed by International Standard Organization （ISO）．It is intended for information integration in Computer Integrated Manufacture Systems and other applications．STEP is not only a specification，but also a technology for information integration．Based on the integration of CAD／CAPP／CAM systems，this paper presents the design and implementation of STEP tool ExTra．This software tool has been used successfully in CAD／CAPP／CAM system integration．