Abstract: This paper analyzes the scale of rural migrant workers with different employment models and their risks of in-work poverty, as well as the mechanism and constraints of in-work poverty based on the National Migrant Population Health and Family Planning Dynamic Monitoring Survey Data of 2017. The result shows that 81% of the migrant workers in the surveyed cities are employed in the non-standard employment model, while only 19% in the standard employment model. Compared with the standardly employed migrant workers, the poverty risk of non-standardly employed migrant workers is 25.6% higher, while the self-employed migrant workers have no significant divergence. Low hour wages is the main labor market mechanism that causes differences of in-work poverty risk among migrant workers in different employment models. As for other factors, both similarities and differences exist among different employment models. The main suggestion of this paper is to deal with the problems of migrant workers' working poverty according to the divergences of their employment models and poverty constraints. On one hand, the labor market policy should be improved by raising the minimum wage level and strengthening the enforcement of labor law; On the other hand, the family policy and pension policy should be improved to raise the degree of de-familiarization and de-commercialization of migrant workers' families.