中文摘要：

关于现实经济中大的垄断企业是否需要拆分一直是一个争议较大的问题。一种观点认为,拆分可以消除垄断,加强竞争,从而促进创新,这将最终有利于提高社会福利。另一种观点认为,拆分使得垄断利润减少,消除规模效应,这可能不利于创新,因而拆分对社会福利的影响是坏的。基于Aghion和Howitt（1992）的熊彼特增长模型,本文考察了拆分对创新、经济增长和社会福利的影响。拆分对研发投资规模和经济增长具有阻碍作用,企业拆分越多,研发投资规模越小,经济增长率越低;拆分对社会福利的影响是不确定的,从社会福利水平极大化的角度出发,垄断企业是否需要拆分取决于竞争性均衡经济中研发投资规模与社会最优经济中研发投资规模的对比。本文旨在运用内生经济增长框架,从社会福利水平极大化的角度出发,为垄断企业的拆分提供一些理论依据。

英文摘要：

There are lots of controversies for whether the monopoly firms should be broken up.Some scholars argue that breaking up may reduce monopoly power,enhance competi-tion,which in turn improve the social welfare.Others argue that breaking up may reduce the monopoly profit,which may reduce the scale effect and have a negative effect on inno-vation.Based on the Schumpeterian growth model of Aghion and Howitt（1992）,this paper tries to find the effect of breaking up on innovation,economic growth and social welfare.We find that,breaking up has a negative effect on innovation and economic growth.With more firms in the intermediate sector,the RD investment level is smaller and the growth rate is lower;the effect of breaking up on social welfare is uncertain,and it depends on whether the competitive equilibrium RD investment is larger or less than the social opti-mum level.This paper intends to provide some theoretical evidence for breaking up the mo-nopoly may improve the social welfare with an endogenous growth model.