The increasing digitalization of manufacturing is transforming product development towards intelligent, service-oriented systems. This study explores the application of Digital Twins (DT) technology in smart Product Service System (sPSS) design, proposing a framework of Super-System Digital Twin (SSDT) and eXtended Reality (XR) for supporting design. The SSDT integrates service offerings, user scenarios, and product features throughout the design process. Case is applied to the conceptual design of a Smart Electric Tourist Bus in collaboration with aglobal manufacturer, the framework utilizes eXtended Reality (XR) environment to enhance decision-making and prototyping. This research validates SSDT’s role in fostering participatory design and collaborative innovation, while addressing its limitations and proposing future improvements.