This paper presents the development of a new high-level design language called Feature based Design Description Language — FDDL. The traditional and computer-aided design and manufacturing procedures were analyzed and the important gaps between CAD and CAM have been identified. These include the lack of uniform representation of parts and products, and lack of effective links between CAD and CAM. The FDDL is proposed and designed in association with a feature representation scheme as a means of integrating design and manufacturing tasks planning. Its syntax, semantics and vocabulary have been defined taking into consideration ease of use, compatibility with engineering terminology and ease of computer implementation. The FDDL system consists of a number of lexical analyzers, a parser and three code generators. Once the products or parts modeled using FDDL or the feature based modeler are processed by the FDDL system, syntax error free input files are created for use by manufacturing task planning systems. The FDDL has been applied to a feature based cellular manufacturing planning system, an expert automated CMM inspection task planner, and a mechanical assembly sequence planner.