Abstract: As a new edition of Grey Systems Analysis by Professor Sifeng Liu is about to be published, I am great honored to write the preface for this classic work in the field of grey systems research. In the mid to late 20th century, human society began to move towards the information age.People are beginning to deeply realize that data analysis methods have become an indispensable skill for everyone.The characteristics and operating rules of various systems are like gold buried in a sea of sand, deeply concealed by the chaotic and complex data information, and there is an urgent need for effective scientific methods to explore and reveal.In response to the needs of the times, as a poverty information data analysis method, grey system theory has emerged. Grey system theory takes the "poor data" uncertain system with "some information known and some information unknown" as the research object. It mainly extracts valuable information through the mining of "some" known information, and realizes the correct description of the system operation behavior and evolution law, so that people can use mathematical models to analyze and assess the "poor data" uncertain system, then realize high-precision prediction, scientific decision-making and optimal control of the "poor data" uncertain system. Prof. Liu has been dedicated to grey system research for 40 years, and his series of original concepts and models have become classics in the field. Such as general grey numbers, simplified forms of grey numbers, and their algebraic systems; Construction and properties of sequence operators and practical buffer operators; A series of grey relational analysis models based on a global perspective; The grey evaluation model based on a mixed possibility function of endpoints and center points, a multiobjective weighted intelligent grey target decision-making model, and a two-stage grey decision-making model based on a kernel weight vector group; And various original poverty information data prediction models such as original difference models, mean difference models, discrete grey models, fractional order grey models, and self memory models proposed in collaboration with his students. Especially his seminal books, greatly promoted the dissemination and development of grey system theory. The Grey System Theory and Its Applications, first published in 1991, were deeply loved by readers. In 2024, Science Press released its 10th edition, which was rated as the first highly cited book in pandect of Natural Science by China National Knowledge Infrastructure. Multiple English versions, such as An Introduction to Grey System Theory(1998, IIGSS Academic Publisher, USA), Grey Information(2006, Springer London Ltd, UK), Grey Systems (2011, Springer-Verlag, DE), Grey Data Analysis (2016, Springer, SG), Grey Systems Analysis (2022, Springer, SG), are the first choice for scholars from all over the world to understand grey system theory and its research progress. Currently, scholars from over 130 countries or regions around the world have published papers on grey systems. My team has been conducting grey system theory research for over 20 years. And starting to publish papers related to grey systems in the early 21st century.We have successfully applied grey system methods and models to solve problems such as construction project evaluation and supplier selection, and proposed multiple combined grey models, such as COPRAS-G, ARAS-G, and EDAS-G, etc. This book will undoubtedly benefit more grey system theory learners and researchers as it is published in OA format with the support of the Excellent Academic Works Publishing Fund of Northwestern Polytechnical University. Grey system theory is a powerful tool for analyzing uncertain data in the era of big data. I look forward to its widespread dissemination worldwide, promoting the in-depth application of grey system theory in the fields of natural sciences, social sciences, and engineering technology.