Abstract: Providing the fullest possible opportunities for all types of working people to compete for jobs and increase their income is one of the basic values of our country‘s innovation development.Based on 2012—2018 China Migrants Dynamic Survey,this paper investigates the impact of the size of the cities to which migrants women enter into the service industry and its possible mechanisms.The empirical results show that for every 1% increase in city size,the probability of migrants,migrant men and women entering the service sector increases by 0.125%,0.098% and 0.152%,respectively.Although married migrants women are significantly less likely to enter the service sector than single migrants women,their probability increases significantly faster than single migrants women as their migration destination city size increases,especially their probability of entering low-end services such as cleaning and housekeeping increases significantly and rapidly,and the results of applying instrumental variables to address endogeneity remain consistent.The mechanism is that the income effect of urban expansion leads to an increase in demand for domestic services,thus increasing employment opportunities for low-skilled migrants women.further improvements and support for labor mobility in the future will contribute to both the improvement of the service industry and employment levels,as well as to the improvement of gender equality and shared development in the social competition system.