The Loess Plateau is divided into 6 agro-ecological and economic systems in this paper. The authors analysed the productivity in each system from many aspects including land use structures, bio-community, productive value structure, energy flow and conversion efficiency in food chains, N-cycle in farmlands, crop water use efficiency as well as water and soil conservation benefits. Also, they proved their viewpoints with the typical examples, and pointed out the directions for the future development. It can be seen from the analysis of the existing conditions that the system of fruit, forests, agriculture and animal husbandry developed in Liang and hill area represented by Miaogou village in Yanan Municipality has the high economic returns owing to a large scale development of apple production, In 1990, per capita net income reached 166.7 Yuan, being 1.9 times higher than that in the surrounding villages. At present, one hectare orchard can support 6.7 persons, being 8.3 times higher than one hectare grassland supports. Up till to 1995, one hectare orchard can support 32.6 persons. In the system of fruit food crops, sideline production and animal husbandry formed in mound and hill area represented by Qianjiagou village in Mizhi county, the modulus of soil erosion has been reduced from 16,000 t/(km²·a). in the 1960s to 3,000 t/(km²·a ). at present owing to a large scale basic farmland construction and conversion of sloping lands into planting trees and grasses. In 1990, per capita net income was 656.4 yuan, being more than double that in the surrounding villages. At present one hectare orchard can support 14.3 persons, being 1.4 persons higher than that supported by one hectare cultivated with food crops. Up till to 1995, one hecgare orchard can support 28.5 persons.