Abstract: A case study in Ansai County of Shaanxi Province in Ecotone between agriculture and animal husbandry in North China conducted by developing a population land equilibrium model that can be applied to a region. Based on the model the population land equilibrium stress formulae were derived. After analyzing the components of agricultural land use, the historical trends of cultivated land, and the food products, the stress of population bearing capacity, cultivated land demands, land productivity, on different food self reliance were calculated on the basis of population prediction and some relevant parameters, taking a step of 5 years within 2000 to 2030. The food self reliance percentages were 100%～70%. Rational food self reliance percentages were proposed, which will facilitate the policy of “returning cultivated land to wood and grass land”, and will put the ecological environment construction into effect.