Abstract: Effective utilization coefficient of irrigation water can reflect the engineering quality，irrigation technology and management level of irrigation area.Head-end measurement method has many advantages，such as simple operation and high dependability，etc.It was widely used in large irrigation districts of China.Take the Sanyizhai irrigation district of Henan as an example，it analyzes the principle of head-end measurement method to calculate the effective utilization coefficient of irrigation water，discusses the calculation process，points out problems in parameter selection when calculating the total amount of irrigation water，crop water requirement，the effective rainfall and groundwater recharge，and puts forward the reasonable suggestions.