This book is the proceedings of the 5th Annual Conference on Fuzzy Information and Engineering (ACFIE2010) from Sep. 23-27, 2010 in Huludao, China. This book contains 89 papers, divided into five main parts: In Section I, we have 15 papers on “the mathematical theory of fuzzy systems”. In Section II, we have 15 papers on “fuzzy logic, systems and control”. In Section III, we have 24 papers on “fuzzy optimization and decision-making”. In Section IV, we have 17 papers on “fuzzy information, identification and clustering”. In Section V, we have 18 papers on “fuzzy engineering application and soft computing method”.