中文摘要：

以扩大中等收入阶层有利于我国经济增长方式向消费驱动型转变为理论背景,首先梳理和计算了国内外定义下的中国中等收入阶层比例变化,发现中等收入阶层的比例大小和变化方向随定义的不同而不同。绝对收入定义下的中等收入阶层的比例一般上升,相对收入定义下的中等收入阶层比例有可能下降,恩格尔系数和基尼系数可作为收入法定义的补充。目前城镇中等收入阶层的比例不足50%,全国和农村的比例更低。然后基于收入拟合方法下的中国收入分布变迁情况得出中等收入阶层比例较低的原因是收入逐渐集中于高收入阶层,最后从收入来源角度提出了降低对中高收入群体转移支付、提高对低收入群体转移支付以及进一步提高低收入者经营净收入等措施以扩大中等收入阶层。

英文摘要：

The changes of the proportion of the middle-income group in China are calculated under different definitions on the theoretical background that raising the proportion of the middle-income group can make China a consumption-oriented society.It is found its international standard and native rectification,the sizes and trends of the proportion are various from different definitions.Under the absolute income definition,the proportion is usually leading a rising trend while under the relative ones it can be decreasing.Engel coefficient and Gini coefficient can act as auxiliary definition.Altogether,the proportion of the middle-income group in urban China is less than 50%but it′s smaller in nationwide or rural area.To observe the actual changes of income distribution in China,fitting method are collected.It turns out that the middle-income group is difficult to be enlarged because the income is converging to the high-income group.Through the decomposition of income resources of all income groups,it is suggested that reducing the transfer income of highincome group,increasing the transfer income of the low-income group and improving low-income group′s net business income can enlarge the middle-income group.