Abstract: Based on China Migrants Dynamic Surveys from 2011 to 2018, this paper examines the fertility level and its changing trend of the floating population, and assesses the influence effect and internal mechanism of the universal twochild policy on the fertility level of floating population. The results show that the fertility level of floating population in China has fluctuated and increased since 2010, and the universal twochild policy has a significant impact on the secondchild fertility level of floating women. However, the accumulation effect of fertility caused by the policy was released quickly. In 2017, the fertility level of Chinas floating population reached a peak of 1.862, which was also the turning point when the fertility level turned from rise to decline. With the gradual implementation of the twochild policy, the secondchild fertility level of the floating population of different socioeconomic status has reversed: the secondchild fertility rate of the floating population with high socioeconomic status is lower at first, and then begins to approach or even surpass that of the low socioeconomic group. Studying the changes of fertility patterns among different groups caused by the universal two-child policy, we may shed light on the longterm development trend of China's population.

Keywords: The Universal Two-Child Policy, Fertility Level, Total Fertility Rate, Progressive Total Fertility Rate

摘要： 基于2011~2018年全国流动人口动态监测调查数据，测算流动人口生育水平及其变化趋势，并重点研究全面二孩政策对流动人口生育水平的影响效应及内在机理。结果表明，2010年以来中国流动人口生育水平总体呈现波动上升趋势，全面二孩政策对流动妇女二孩生育水平影响较明显，但政策调整所形成的生育堆积效应释放较快。2017年中国流动人口生育水平达到峰值，孩次递进总和生育率为1.862，此后，流动人口生育水平由升转降。随着二孩政策的逐步实施，不同社会经济地位流动人口的二孩生育水平发生了逆转，高社会经济地位流动人口的二孩生育水平先是低于，随后开始接近甚至反超低社会经济地位流动人口。深入研究全面二孩政策带来的不同群体间生育格局的变化，有助于把握中国人口长期发展趋势。

关键词: 全面二孩政策, 生育水平, 总和生育率, 孩次递进总和生育率