Abstract: The characteristics of energy flow 19 household agri-ecosystems were analyzed based on energy ecology.The result indicated that the energy flow of agri-livestock type,agri-forest type,comprehensive type and agri-sideline type could be divided into energy input from outside system,bio-energy flow among subsystems and the bio-energy output from the system.The four types of farmland subsystem,with petrol-agriculture characters,input high inorganic energy.The level of energy input in animal husbandry subsystem was determined by the food energy.

Key words: loess plateau, household；agri-ecosystem, energy flow, bio-energy