Abstract: There were not only the contradiction between agricultural industry and ecological construction resources competition,but also the problems that need to be solved urgently for economic growth and sustainable ecological improvement in the northern agro-pastoral ecotone. Under the guiding principle of "clear water and green mountains are gold and silver mountains",this paper studied the strategy of giving priority to ecological construction and consideration to economic development of agricultural industry with the perspective of opportunity cost theory. Through the analysis of opportunity cost,externality and Pareto optimal theory,and the ecological service value of forest,grassland and farmland was calculated by using the calculation method of unit equivalent factor value of terrestrial ecological service function. The results showed that:The ecological value of forest and grassland per unit area was greater than that of agricultural industry. Therefore,the opportunity cost of afforestation and grass planting was less than that of agricultural industry. Based on the theoretical analysis and quantitative analysis,some suggestions were put forward to construct the comprehensive system of giving priority to the ecology and consideration to the development of agricultural industry,and to establish and perfect the incentive mechanism of ecological construction.

Key words: Opportunity Cost, Northern farming-pastoral Ecotone, Agricultural Industry, Ecological Construction, Coordinated Development

摘要： 北方农牧交错带既存在农业产业与生态建设资源竞争的矛盾，又存在经济增长与生态持续改善亟需解决的问题。以“绿水青山就是金山银山”发展理念作为生态优先、绿色发展实践的指导原则，该文从机会成本理论切入，研究优先生态建设兼顾农业产业经济发展策略问题，通过机会成本、外部性、帕累托最优理论分析，以及应用陆地生态服务功能单位当量因子价值量计算方法对森林、草地、农田的生态服务价值进行核算，结果表明：单位面积森林、草地的生态价值大于农业产业的生态价值，因此说明农地用于造林和种草等生态建设的机会成本小于从事农业产业的机会成本。依据理论分析与量化核算所得结论，提出构建生态优先兼顾农业产业发展的综合体系，以及建立与完善生态建设激励机制的建议。

关键词: 机会成本, 北方农牧交错带, 农业产业, 生态建设, 协调发展