Abstract:    With the change of the structure of scientific knowledge, the scientific paradigm of seeking knowledge has been reconsidered and developed. Breaking the division of disciplines that are over-segmented and isolated, and responding to increasingly complex design sciences in an interdisciplinary and integrated approach is more than ever. In this case, relying solely on the designer′s experience and intuition can no longer effectively solve complex design practice problems, but more and more frequent and active "design science" are needed. In order to meet the needs of social development, it is necessary to explore the hotspots of design science from the existing literature research results, which is conducive to the systematic construction of design science. Design science combines scientific research paradigm with designer-style thinking, which has attracted many scholars′ attention. However, the current research results are basically based on qualitative and speculative methods, so far there is still a lack of multi-index, quantitative and systematic research on the "hot spot of design science and its evolution trend". 
   This paper uses the bibliometric method to visualize the literature results. On the one hand, it can effectively overcome the subjective one-sidedness caused by the single experience summary, solve the differences and confusion in the development of design research, and provide new ideas for the review of the discipline literature of design research. On the other hand, this paper studies the hotspots and frontiers of design science based on open and transparent authoritative data, which is conducive to clarify the inner theoretical framework and logical structure of design science, and then proposes new research perspectives and paradigms for the development of interdisciplinary theory. It takes the design science Chinese literature published by the National Natural Science Foundation from 1997 to 2017 as the research object, and uses the bibliometric method and the visual analysis software such as VOSviewer and CiteSpace V to conduct statistical analysis and content mining on the design scientific literature. 
    Firstly, it reflects the knowledge distribution rule of design research by mining the co-occurrence relationship between high-frequency words, and studies the hot spot and direction of design research based on cluster analysis of co-word network. Then the citation analysis is carried out by using the reference data. By drawing the citation time series map of design science, the frontier and trend of design discipline are studied intuitively and deeply. Finally, through comprehensive and comparative analysis, the design scientific knowledge graph system is constructed. In this paper, the macroscopic and microscopic knowledge structure, the evolution law and the development trend of the design science field are interpreted in the way of data visualization, and the reference for the scientific research direction and the research focus is provided for the scientific researchers. 
   The research results show that: firstly, in the past 20 years, the number of literature on design science in China has been increasing step by step with time, and the degree of design scientific research and the degree of attention have been increasing continuously. In the past 20 years, Northwestern Polytechnic University has produced the largest amount of literatures in this field, followed by Zhejiang University, Software Research Institute of Chinese Academy of Sciences, Sichuan University, Tongji University, Shanghai Jiaotong University, Hebei University of Technology，Hunan University and other institutions which have  established the first batch of design majors in China. Keywords such as conceptual design, product design, human-computer interaction, and innovative design have the highest frequency in design science. 
   Secondly, the six hot areas of design science research are design theory and methods, conceptual design, emotional design, intelligent design, interaction design, and ergonomics. Conceptual design and design theory and methods provide a core idea for the development of design science. The field of human-computer interaction and computer, network communication, anthropology and other fields are intertwined, which profoundly reflects the interdisciplinary nature of design science. Personalized emotional design is closely related to conceptual design, and it is a research hotspot in recent years. The field of intelligent design focuses on the expression of knowledge and the reasoning of concepts, and is strongly associated with the field of conceptual design. The knowledge base in the field of ergonomics mainly comes from engineering psychology, anthropometry, technology aesthetics and so on. The various fields of design broadly integrate the theories and methods of various disciplines, and realize the orderly inheritance and evolution of the internal knowledge of design, and the integration, reorganization, creation and appreciation of interdisciplinary knowledge. It reflects the cross-disciplinary and innovative nature of design. 
    Thirdly, the development of design science research has gone through four stages: research awareness awakening period, research foundation period, research expansion period and research depth period. During the awakening period of the research, the heat and attention of the design research began to rise, the conceptual design research was enriched and developed, and the characterization of the emerging design cognitive research direction began to awaken. It injects vitality into the development of modeling and reasoning technology applications and conceptual design studies for analyzing product information. In the research foundation period, design science research focuses on axiomatic design, which lays a foundation for the orderly inheritance and evolution of internal knowledge in design science research. In the research expansion period, design science research has gathered into emotional design. Grasping the user′s emotional tendency and humanistic care in design has become a new hot spot in design science. In the depth of the research period, scholars examine and reflect on the problems existing in the research, trace the source, and turn to new questions such as the inner cognition of design and the way of thinking.

Key words: design science, knowledge graph, science fund, research frontier, evolution trend