The invention discloses a variable irrigation management decision-making method, which comprises the following steps: S1, carrying out soil sampling on crop root zones in a control area of a sprinkler, and measuring the size fraction composition of the sampled soil; S2, performing management zoning on the control area of the sprinkler according to the available water content (AWC) of soil in the crop root zones; S3, constructing an optimized soil moisture sensor network; S4, arranging a ground fixed canopy temperature sensor; S5, constructing an optimized airborne canopy temperature sensor network by taking the central fulcrum shaft as a circle center; and S6, conducting variable irrigation through the optimized soil moisture sensor network, the fixed canopy temperature sensor, the optimized airborne canopy temperature sensor network and an automatic weather station. According to the variable irrigation management decision-making method, the arrangement positions and the number of the soil moisture sensor network and the canopy temperature sensor network are optimized, the measurement precision is improved, and the cost of a variable irrigation system is reduced.