中文摘要：

长期以来，主流经济学的假设是规模报酬不变和完全竞争。但从20世纪六七十年代开始，人们意识到，规模报酬递增的生产技术和垄断竞争的市场结构才是经济生活的常态。如何以规模报酬递增和垄断竞争为基本假设构建理论模型成为当时经济学理论发展的技术性难题。1977年Dixit—Stiglitz模型（D—S模型）以简单、巧妙而严谨的方式将规模报酬递增和垄断竞争纳入到一般均衡模型，这个突破引发了一场经济学理论建模的思想解放。此后，以D—s模型为基础，新产业组织理论、新贸易理论、新增长理论和新经济地理学等经济理论获得了巨大发展，并对许多其他涉及规模报酬递增和垄断竞争市场结构的研究提供了新的思想平台。

英文摘要：

For a long time, the assumptions of mainstream economics are constant returns to scale and perfect competition. However, from the sixties and seventies in 20th century, people were aware that production technology of increasing returns to scale and monopolistic competition of market structure was normal in economy. How to build a theoretical model for the basic assumptions of increasing returns to scale and monopolistic competition became a technical problem in the development of economic theory. Dixit-Stiglitz model （D-S model） makes the increasing returns to scale and monopolistic competition with simple, ingenious and rigorous manner into general equilibrium model in 1977, and this led to a breakthrough of modeling emancipation in the mind in economic theory. Since then, the new theories of industrial organization, new trade theory, new growth theory and new economic geography gained tremendous development based on D-S model, and it provided the research platform for many others issues related to increasing returns to scale and monopolistic competitive of market structure.