Accurate acquisition for customer’s requirements is the base and key in product configuration design. However, original customer’s requirements must be decomposed in order to comprehend truly and apply them to guide product configuration design, because they are usually some fuzzy, general even contradictory customized demands. In the paper, two concepts are introduced for customer’s requirement decomposition. One is the requirement element, and the other is the granularity of requirement element. Moreover, the controlling principle for granularity of requirement element is given and the method of requirement decomposition is proposed. This method means semantic segmentation, semantic translation, supplement or subdivision of human-machine-environment and semantic combination. Customer’s abstract demands could be effectively decomposed into some specific requirement elements according to the proposed method of requirement decomposition as well as by controlling the granularity of requirement element reasonably. Finally, the customized design of a money-binding machine is taken as an example to validate the effectivity of proposed method.