Service design has been an emerging transdisciplinary field that includes product, system, and social science, since the term was first introduced to academic research in the early 1990s. With socioeconomical shifts and emerging technologies, people have faced more complex and systemic challenges, which enable researchers to consider how to reapply service design not only as problem-solving tools but also as ways for communication and alignment to adapt to the change. The study focuses on the paradigm shifts of service from its definitions to applications by interviewing nine design experts from academia and industry, and utilizing survey results to help us explore applying service design to solve complicated social-technological challenges. We present four takeaways: 1) a new understanding of service design, 2) the purpose of using service design tools, 3) the evaluation of service quality through time, and 4) the applications of service design in the public sector. We proposed a macro-trend model with service systems: product, service, and experience to conclude 1) constructing service systems in the macro-trend context and 2) gaining holistic views and building service implementation capability in the era of transformations.