In order to improve complex shape piston productivity computer integrated manufacturing system (CIMS) technology is presented. Design elements need to be taken into account in CIMS technology, which are geometry, material choice, and rationalization of components (reducing assemblies) and cost. In design freedom phrase, this new design freedom will place much more responsibility on the designer to think about the exact requirements of a part – with the unlimited geometry capability designers will therefore need to be much more imaginative to make full use of the new manufacturing processes. New design paradigm is presented and mechanical designers will be able to manufacture any complexity of product they require. Effect of graded materials on product design is considered and 2D and 3D of piston are carried out. CAD issues and assembly constraints of complex shape piston of diesel engine are discussed. It gives new method to design and produce complex shape piston of diesel engine.