Abstract: This paper analyses the development level and trend of grey system theory (GST) over the past 40 years based on bibliometrics. Literature was searched using the Web of Science (WoS) databases. Literature analysis was carried out from eight aspects: paper publication, main journals publishing GST and its application, 20 highly cited articles, hot research topics, high-output scholars and their cooperation networks, the geographical distribution of scholars, funding agencies, and a comparison between papers obtained from the China National Knowledge Infrastructure (CNKI) and WoS databases. Bibliometric analysis showed that while GST had developed slowly over the initial 20 years, it experienced a period of high-speed development over the last 20 years. Two journals—the Journal of Grey System and Grey Systems: Theory and Application—play key roles in promoting the international development of GST. Professor Sifeng Liu and Nanjing University of Aeronautics and Astronautics have been the most influential scholar and research center in GST, respectively. GST has attracted many scholars worldwide, and the number of papers published in international journals is increasing. A comparison of publications related to GST between CNKI and WoS databases showed that more efforts are required for GST to become more international.

Key words: Grey System Theory, Bibliometrics Analysis, WoS, CNKI, Research Situation