Abstract: The constant upgrading of market competition forces enterprises to extend the product value to the product life cycles (PLC). This brings about more opportunities for product innovation and benefit, while makes the product decision more difficult in the meantime. A product planning decision framework is firstly set up along the entire spectrum of PLC on the basis of the concept of design domains to reflect the systematic characteristics of the PLC and to promote the integration of the analysis on the customer needs, the design conceptions, the analysis on product realization and after-sales maintenance. Secondly, by the case of the generational design, the metrics for PLC-based decision are presented and the modeling method is explored to effectively demonstrate the trade-off mechanism. Lastly, by way of illustration, a product example of family sedan is planned and its results demonstrate the effectiveness of the modeling. The presented method sets up the decision mechanism oriented by the establishment of information connection among the different department in the company and should show its practical value by forward application.

Key words: design domains, family sedan, product life cycles(PLC), product planning, product value