Since it came into being, UML (Unified Modeling Language) has become a common tool for Object-Oriented Analysis and Development (OOA&D) and a kind of industrial criterion. Today it is widely used in many fields. Based on the basic principles and methods of farmland gradation, taking the composite geographic information system as the platform of system development and using UML techniques, this paper analyzes and models the Farmland Gradation Information System from aspects of demand capture, system analysis, system design and realization. ...