Abstract: Evaluating the impact of income inequality on economic growth is critically important to judge the reforms of Chinas income distribution system in all development stages. This paper incorporates income inequality into the framework of Unified Growth Theory and constructs a theoretical model that endogenously determines population size, inequality and economic growth. The empirical study is carried out using China's provincial panel data and the income inequality index is constructed based on the CGSS data. Empirical results show an inverted Ushaped relationship between inequality and economic growth. Moreover, the inverted Ushaped curve gradually moves to the leftside as economy develops, suggesting that the optimal inequality reduces in pace with the development of the economy. These findings suggest that, since the reform and opening up, Chinas income distribution system reform in each period is the optimal choice under the specific historical conditions. The conclusions of this paper have profound policy implications: the achievements of eliminating poverty should be consolidated and the income inequality should be reduced in line with economic development.

Key words: income inequality, economic growth, income distribution, economic development level

摘要： 准确判断收入不平等对经济增长的影响，对于客观评价中国各个阶段的收入分配制度改革尤为重要。本文在统一增长理论的框架下引入收入不平等因素，构建了一个人口数量、不平等和经济增长同时内生的理论模型，并利用CGSS数据构造收入不平等指标，使用中国省际非平衡面板数据进行经验检验。研究发现：收入不平等与经济增长之间呈现倒U型关系。更重要的是，随着经济发展水平的提高，倒U型曲线将逐渐向左移动，即最优的收入不平等程度随着经济发展水平的提高而逐渐降低。这一发现意味着改革开放以来，中国各个时期的收入分配制度改革均是在特定历史条件下的最优选择。本文的结论具有深刻的政策含义：为了提高经济增长率，需要进一步巩固“脱贫攻坚”成果，逐渐加大收入分配调节力度，使收入分配制度改革紧跟经济发展的步伐，根据经济发展水平不断缩小收入不平等程度。

关键词: 收入不平等, 经济增长, 收入分配, 经济发展水平