Customers limited knowledge and technique restrains manufacturer from making them directly participate in practical product design to quickly respond to their complex and personalized demand. Based on design iteration, an approach to customer-oriented product collaborative customization is proposed for manufacturer to improve the design process. This approach uses the existing product and continuously increasing product design scheme as valuable product configuration knowledge. Meanwhile, the concept of product family is extended to design family, where the product individual and design scheme are respectively distributed into different knowledge bases. With the benefit of iterative genetic algorithm (IGA), design iteration is applied to make the existing product and design process bi-directionally evolve in the customized process to seek the optimal design, accordingly customers' operational fatigue will be lessened and their customized efficiency will be improved. Finally, the customized design of tablet PC is taken for instance to testify the maneuverability and effectiveness of the proposed approach. The experimental results demonstrate that the approach could effectively identify customers' preference and obviously improve their customization efficiency, with lessening their operational fatigue to the large extent.