This paper presents a study on the theory and methodology of safety assessment of Yangtze dike. The main topics discussed and the conclusions of the study are as follows: (1) The function and makeup of Yangtze dike are summarized systemically and status and incipient fault of the dikes are discussed. (2) The frame of safety assessment of Yangtze dike is proposed, consisting of three categories of safety assessment (namely, risk analysis, conventional mechanical evaluation,and comprehensive evaluation). (3) The main factors affecting safety of Yangtze dike are discussed systematically. Index system and assessment methods are proposed. On the basis of AHP (The Analytic Hierarchy Process) with fuzzy theory, a new method for comprehensive assessment of Yangtze dike is put forward. (4) A software with programming language Delphi for the safety assessment of Yangtze dike is developed and automation and visualization for the assessment of dikes can be realized.