在我国城市化过程中,城市内部同时存在着正规部门和非正规部门。进城农民工由于人力资本、户籍制度等方面的限制,难以进入城市正规部门,只能进入非正规部门就业。城市化因此体现为农民从农村向城市非正规部门的流动,以及城市中非正规部门人口比重的不断提高。由于人力资本的差距和政府以户籍为基础的政策倾斜,非正规部门的收入要低于正规部门。这个特点在一定条件下将导致城市内部收入差距的单调上升。要避免城市化对城市内部收入差距产生负面作用,就必须消除城市内部的二元劳动力市场。这就要求政府放弃以户籍为标准歧视进城农民工的政策取向。

During the process of China's urbanization, there exist high-income regular sector and low-income irregular sector simultaneously. Being restricted by human capital, social capital and the institution of residence, most of the peasants who come into the city can not be accepted by regular sector and have to come into isregular sector. Therefore the urbanization becomes a flow from village to the urban irregular sector, and a monotonic increase in the relative population of irregular sector, which would tend to enlarge the within-urban inequality under specific conditions. The hypothesis has been supported by the empirical test.