Abstract: Conventional water saving control for farmland irrigation mainly uses impact factor analysis to simulate accuracy of farmland irrigation to obtain a water saving control plan for farmland irrigation, ignoring impact of actual liquid limit and plastic limit variables of farmland soil on control plan, resulting in a low water saving coefficient of water saving control results．A water saving control method for farmland irrigation based on time-varying nonlinear characteristics and state variables was proposed．This method calculated time-varying nonlinear characteristics of basic parameters of farmland soil, calculated constraint conditions based on analyzed characteristics, established a target constraint function, and constructed a water saving control model for farmland irrigation, calculated target constraint conditions of state variables of farmland soil liquid limit and plastic limit to re evolve model, and obtained final water-saving control plan for farmland irrigation．Experimental results showed that water saving control results obtained after application of proposed method exhibited a high water saving coefficient, with an average of 0.477, water saving effect was good and met practical application needs of farmland irrigation．