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.