Abstract: Pressure regulator is one of the key parts of micro-irrigation system, which can improve the water distribution uniformity and running security obviously. In this paper, the author firstly analyzed the structural parameters which affected the working performance of pressure regulator through analysis of the dynamic balance on pressure regulator. The analysis result showed that the main factors that affected the performance of pressure regulator were the spring coefficient, the spring length, the upriver and downriver areas of regulating part and the space between regulating part and block cap. On the basis of analysis result, the author adopted orthogonal experiment to analyze the effects of structure parameters on the preset pressure. The results revealed that the four parameters had notable influences on the working performance of pressure regulator. In addition, the regression model describing the relationship among the four factors and preset pressure was developed, which had good linear relationship and would provide reference to the production of pressure regulator.