Among a dam safety monitoring data, there might be some abnormal values which have important influence to the appraisal for the structural condition and the safety monitor of the dam, so the work is needed to be done to identify and deal with them. This paper has researched the methods of identifying and dealing with the abnormal values in theory, and solved some key technological problems in identifying and dealing with abnormal value by computer, and set up the module which identifies and handles the abnormal values for the dam safety information management system.Engineering application shows that the module possesses friendly, visible user interface and the capacity of effectively identifying treatment. 