Abstract: Based on the theory of variance estimation of mathematical statistics, the parameters of irrigation uniformity in full equalizing micro-irrigation system were studied and the relational expression between coefficients of the irrigation uniformity and the flow deviation were proposed. At the same time, the formula was validated using simulation method with conventional random numbers and the relationships between the coefficients of irrigation uniformity and the flow deviation were discussed. The application worth of the formula was indicated through an example. The research provides reference for the plan of micro-irrigation system, appraising irrigation uniformity and controlling manufactuerable deviation of equalizing emitter.