Abstract: The relationship between conformable functions and overall functions of agro-eco-system was analysed in this paper.It was pointed out that functional conformability is the essential character of an agroecosystem.The improvement of the overall functions of an agroecosystem depends on the improvement of its conformable functions which would be carried out by optimizing the system structure.Then conformable functions of an agro-eco-system can be taken as a key index for judging the performances of the structures and overall functions of the agroecosystem.