Participation in basie medical insurance for urban workers and trade union participation are important elements for migrant workers torealize the same rights as local urban workers. These issues are related to the progress of migrant workers' citizenship. Based on the 2017 CMDSdata,this study examined the impacts of trade union participation on the participation rate of migrant workers in urban medical insuranee. The resultsof the study found that: 1 )The participation of migrant workers in trade union activities has significantly increased the participation rate of theirurban employees basic medical insurance and the conclusion is still significant after the Propensily Score Matching. 2 )The trade union participationin promoting basie medical insuranee for urban employees has a significant effect on intergenerational migrant workers, and a greater impact en theolder generation of migrant workers. To better protect the labor rights and interests of migrant workers, it is proposed that more attention should bepaid to the construetion of labor unions to promote migrant workers'broader coverage in their basic medical insuranee.