Abstract: Based on the four outstanding characteristics of agricultural ecosystem Clarge amount of input and output; large quantity of auxiliary energy flow; shortened food chains; extended detritoiis chains) and the relationship of materials and energy flow between agricultural enterprises, the author proposed that the combination of agricultural ehterprises was the foundation of effective and multiple utilization of materials and energy in agricultural ecosystems. But this did not mean that all agricultural ecosystems made up of several agricultural enterprises could achieve promising results. In order to achieve the best result and to set up new systems in which materials and energy can be best utilized withi high effects and low. costs, seven general principlss were discussed; 1. Principle of adoptation to the local environmental condiitions. 2. Principle of determining reasonable numbers of agricultural enterprises. 3. Principle of pushing forward the key enterprises. 4.Principle of maintaining a suitable auxiliary energy flow. 5. Principle of expanding population of producers. 6.Principle of rational space arrangements. 7.Principle pf strengthening pest control.