This paper establishes a PDM–based integrated design system IDEF0 functional model. The system consist four charts: A-0 chart, A0 chart, A1chart and A2chart. A-0chart defines the range of the system; A0 chart includes 4 modules (task granting, outline design, detail design, evaluation); A1chart and A2 chart decompose and illuminate detail design module and machining processing design module. The system can be easily adapt and applied to many domains of product design and engineering design.