中文摘要：

城市增长具有规模效应和拥挤效应。不同城市规模下，进入城市的外来劳动力与本地市民既可能形成分工合作关系，促进本地市民收入增长；又可能形成竞争替代关系，导致本地市民收入下降。文章使用中国社会综合调查开放数据库（CGSS2008）中城市抽样调查数据，研究发现外来劳动力流入对特大城市本地市民工资的影响不显著，而外来劳动力每增加1％就会使省会级大城市本地市民的年薪提高1．46％，中小城市本地市民的年薪下降0．83％。因此，外来人口与城市本地市民之间的关系表现为，特大城市互补效应与替代效应同时并存，大城市（省会）表现为互补效应强于替代效应，中小城市则替代效应强于互补效应。

英文摘要：

The city growth has scale and crowding-out effects. In cities with different scales,migrant workers may be the collaborators of local residents, leading to the increase in the income of local residents, and also may be the competitors of local residents, giving rise to the reduction in the income of local residents. Using the city survey in CGSS2008 database, this paper con- cludes that the inflow of migrant workers has no significant effect on the wages of local residents in mega-cities, while the increase in migrant workers by 1% leads to the rise in annual wages of residents in provincial cities by 1.46% and the reduction in annual wages of residents in small and medium-sized cities by 0.83%. Therefore, the relationship between migrants and local residents is featured by coexisting complementary and substitution effects in mega-cities, complementary effect stronger than substitution effect in big cities （like metropolis） and substitution effect stron- ger than complementary effect in small and medium-sized cities.