As an important factor restricting the development of social insurance, labor relations have great impacts on pension insurance. Thisstudy, based on the 2016 dynamic monitoring survey data of national migrant population (CMDS),explored the impact of labor relations on pensioninsurance participation of the rural migrant population, and conducted a heterogeneity test. The results of the study showed that labor relationssignificantly affected endowment insurance participation of the migrant population. This could be seen as the higher the income level of themigrant population was and the more formal the employer was, the higher the probsbility of participating in insurance was; the probability of sell-employed participation was higher than that of other employees; and whether to sign a labor contract was directly proportional to the probability ofparticipation. Moreover, labor contracts and monthly income, as an important part of labor relations, not only directly affected endowment insuranceparticipation, but also had a significant impact on it as intermediary and moderating variables. Hence, from the perspective of labor relations, thereare feasible ways to enhanee the level of insurance participation: One is to gradually achieve full coverage of labor contracls, whilst the other is toincrease the income level of workers.