Abstract: Based on the knowledge and understanding of modernization of the physical irrigation district and digitalization of the analog irrigation district, this paper analyzes and summarizes the “five major functions” of the construction of modernized digital irrigation district including “Identification system of irrigation district”, “Stereoscopic Perception System”, “Precise Control System”, “Information Exchange System” and “Water Allocation System”. In order to meet the requirements of intelligent water projects and efficient operation and management of irrigation district, to efficiently simulate water flow in canal system, the generalized map of irrigation district with “joint flow process” as input and output is systematically sorted out, and the key application structure system of modernized digital irrigation district is studied and proposed. That is to build an interactive overall structure with “database” as the carrier, “mathematical model” as the support layer, “nine professional applications” as the interaction layer including “organization management”, “project management”, “security management”, “pumping station management”, “water saving and water supply management”, “economic management”, “information management” and “public services” on the basis of “one digital map of the irrigation district”. It is expected to effectively improve the safety, equity, reliability and flexibility of irrigation water supply services.