Abstract This paper describes representation and manipulation of designers' intent which is effective for supporting efficient product design in CAD systems. Due to the recent demand of high-quality products, it becomes necessary to tightly integrate design and manufacturing preparation works to realize maximum performance of products under several manufacturing constraints. Design intent plays an important role to give good communication media between product designers and manufacturing engineers. In this paper, the new architecture for flexibly integrating the whole engineering activities is proposed, where the required engineering activities can be processed concurrently. All the necessary product information is represented by a product model, in which design intent is one of the most important information. Representation based on logical constraint and its solution methods are introduced for the basic tools to deal with design intent. They can be applicable to general product design, but, for demonstrating the effectiveness of the approach, a practical system is explained for geometric shape design, and some examples are shown.