During the operation period of earth-rock dam,the dam safety monitoring system is set up for scientific observation on time,and scientific data analysis and health diagnosis are conducted to find problems in time,so as to avoid or reduce engineering accidents as far as possible.Based on the large reservoir dam safety monitoring data analysis experiences in many years,the dam safety monitoring content,main monitoring items,and common observation instruments in dam safety monitoring are introduced,and the common data analysis method for the monitoring physical quantity,including seepage pressure,deformation,stress-strain and temperature are discussed,providing references for safety monitoring data analysis of earth-rock dam in operation.