Empirical test indicates that the relationships between migrant work，migrant workincome and development are not definite，and exert differential influence on different ethnic groups. For all ethnic groups，migrant work income increases overall average income，but also causes higher-level poverty and intra-ethnic group income inequality. Results show that migrant workincome has the influence more favorable for well-off families，namely only relatively well-off families can benefit from migrant work，while poverty-stricken families are impaired by migrant work in fact. Compared with the “penetration” concept of migrant work，the finding supports the concept of immiserizing growth，namely the negative effect caused by growth driving will reduce overall social welfare.