Abstract: Food production system in Chengczhuang village near Beijing was studied in viewpoint of energy and substance flow . Quantitative characters of energy and substance flow arc summarized . The parameters of food productivity and efficiency of resource utilization arc obtained . The carrying capacity of human population in the system under various diet structure is analysed . It is suggested that food diet with a major proportion of vegetable protein is the appropriate consume system in the place . Measures for further improvement of the system arc proposed .