Abstract: A method and system for generating a variable rate irrigation (VRI) prescription map for a large sprinkler irrigation system is provided. The method includes: determining a minimum length of a VRI management zone along a truss direction of the sprinkler irrigation system; determining a minimum angle of the VRI management zone along a travel direction of the sprinkler irrigation system; dividing the VRI management zone to generate a VRI management zoning map; determining, according to a basic irrigation amount of VRI management and a spatial distribution map of crop water deficit or a spatial distribution map of soil water holding capacity (SWHC), an irrigation quota of each management sub-zone; and generating, according to a distribution map of irrigation quotas of all management sub-zones in combination with a travel speed of the sprinkler irrigation system and a duty cycle of a solenoid valve, the VRI prescription map.