城市流动农民（又称流动人口、外来人口）已出现二次分化。所谓二次分化，是指改革以后，在原来意义上的农民分化为若干职业群体后，作为其中一个统一身份群体的流动农民内部的再分化，即形成若干类别群体或等级群体的过程。我们研究表明，在过去十多年里，流动农民这一群体的 Urban migrant farmers (also known as floating population, migrant population) have appeared second differentiation. The so-called secondary differentiation refers to the process of the reintegration of migrant peasants who are one of the unified identity groups after the reform in the original sense of differentiation of the peasants into a number of professional groups, that is, the formation of a number of categories of groups or levels. Our research shows that this group of migrant peasants have been in the past decade or so