Product modular design can improve the efficiency of product development, reduce the cost of product design and improve design resource utilization, and keep the high quality of product to response market and meet the personalized needs of consumers. In order to solve the clustering problem of the largescale Design Structure Matrix (DSM) model, a modular approach based on the genetic algorithm has been proposed. Firstly a product structural DSM model was built through comprehensively considering the functional and structural interaction between the product components. Secondly the modularity was designed for the fitness function. Lastly, the best clustering result was calculated by the genetic algorithm and the intelligent clustering partition of product structure’〖KG-*2〗s DSM model has been achieved. A clustering case on vacuum cleaner parts modular is examined to be feasible by the proposed method.