Abstract: From the view of system engineering, the paper advanced a system of planning theory and methodology of "one guide and three sets" for agricultural engineering planning, and constructed a six-dimension framework for evaluating the investment on and the environment of agricultural engineering. By using the system and the framework in the study on agricultural engineering planning in Inner Mongolia, it is concluded that agricultural engineering planning should include the following three parts: the system of planning theory and methodology, planning contents, and countermeasures.