The increased competitive pressure forces companies to cease distinguishing products and services, and to provide customers with highly individualised solutions. To meet this requirement, it has been proposed the concept of product–service system (PSS) that is not simply an extension of physical products by delivering non-physical services to customers, but a systematic combination of products and services. However, most current studies do not consider the multi-disciplinary integration relating to the PSS design process, during which the collaboration within the product and service design teams should be achieved. Otherwise, the large number of iterative design activities resulting from poor multi-disciplinary collaboration may lead to long development lead-times and high development cost. To achieve the multi-disciplinary integration during the PSS design process, the authors propose an integrated design method using an improved interface modelling approach that provides a structural form to represent the information transfer between product and service components. The proposed PSS design method enables the product and service design teams to decrease the iterative design activities and improve their collaboration so that a more integrated design process can be accomplished. To demonstrate its effectiveness, the design method is applied to a design case of an industrial PSS.