中文摘要：

人口政策作为影响人口动态变化的重要变量,普遍放开二孩会对中国人口数量、人口质量和人口结构产生重要影响。文章通过对未实施普遍二孩政策和实施普遍二孩政策两种生育方案下未来中国人口规模、人口结构进行预测。发现：（1）实施普遍二孩政策将有助于减缓我国人口规模急剧下降趋势,缓解人口老龄化压力,实现未来劳动力资源的不断供给,平衡人口性别结构,人口性别年龄结构趋于均匀至少需要84年时间;（2）出于成本考虑,普遍二孩政策可能会造成生育阶层化,而影响未来我国人口素质的提高;（3）解决生育阶层化的有效途径是健全社会保障制度,提高社会福利水平。

英文摘要：

As an important variable,population policy will affect population quantity and population structure dynamics. Based on universal two-child policy,we predicted the dynamics of China＇s population size,and population structure.We found that： firstly,the common two-child policy will help to slow down the population decline sharply in our country and alleviate the pressure of the population aging,supply the future labor force resources,and balance gender population structure. However,it will take at least 84 years that population age and gender structure tend to be balanced; Secondly,in view of the cost,generally two-child policy may lead to reproductive stratification,and affect the quality of the population in China; Thirdly,the effective ways to solve fertility stratification are perfecting social security system and improving the level of social security.