Irrigation water utilization coefficient refers to the ratio of the net water used by crops during one irrigation period to the total imported water at the head of the water source.For effective utilization coefficient of irrigation water calculation and analysis will help to further clarify the main direction of agricultural water saving,water-saving irrigation overall plan for the government to promote the coordinated development and overall progress of the cause of water-saving irrigation to provide reference.Taking Yandu District,Yancheng as an example,reasonably selects the sample tank area,and calculates the utilization coefficient of farmland irrigation water in 2020 to be 0.670 through direct measurement method,which truly reflects the irrigation water efficiency of farmland in Yandu District,and the result can be water saving reconstruction,agricultural irrigation water management and rational allocation of water resources,and provide scientific basis for decision-making on water resources issues.