Mathematic model of agricultural eco-engineering is to represent the knowledge of system*s present situation, function and structure. Based on study and analysis, a mathematic model of medium-sized agro-ecological engineering—Liuminying ecological agro-systemisis established. This system consists of eight branch rooms. The state variables and the control variables for each branch room are given and the mathematical models for the branch rooms are also built. The mathematical model has been applied to guiding the pratical production in Luiminying Villnge and satisfactory results are achieved.