Platform and module planning results using traditional methods are usually not consistent with the actual situation in product family design (PFD). Research was conducted involving modularisation theory and implementation methods to overcome the difficulty of platform and module dynamic planning/re-design for mass customisation (MC). A graph-theoretical approach was also developed in PFD. Firstly, the commonality and the physical structure of the existing product variants were analyzed in a product family. Part commonality and the physical structure of similar products were then modelled using a directed and an undirected graph, respectively. According to market demands, different platform thresholds and boundary parameters of modules