“Health for all” is the fundamental purpose of the Healthy China strategy，and mental health provides the necessary human capital foundation for achieving rural revitalization and preventing poverty return.Based on the stress process theory，744 micro research data of migrants relocated for poverty alleviation in County J of Hubei Province in 2021 were used to construct social adaptation indicators from four aspects：livelihood development adaptation，basic life adaptation，interpersonal interaction adaptation，and affective adaptation，focusing on analyzing the impact of migrants’ social adaptation on their mental health，and empirically examining the moderating effect of the area of arable land prior to relocation.The study shows that，firstly，the mental health risk of migrants relocated for poverty alleviation is a key issue that needs urgent intervention in the comprehensive revitalization of the countryside，and livelihood development adaptation is the prominent shortcoming of social adaptation；secondly，social adaptation has a significant positive impact on mental health，and there is a group difference in this impact effect，and the mental health improvement effect of social adaptation is limited in the old age group，the non-urban resettlement group，and the group with no non-agricultural work experience； furthermore，the arable land is the key element of farmers’ livelihood development and emotional support for farmers who “live by farming” and “work by farming”，relocation will cause an off-site shock to them，and this effect is magnified with the expansion of cultivated land area prior to relocation，and the greater the off-site impact of relocation，the more pronounced the effect of social adaptation on mental health after relocation.These results hold even after using instrumental variables to mitigate endogeneity.Based on this，in promoting the construction of a healthy China，implementing rural revitalization and consolidating the achievements of relocation for poverty alleviation from the perspective of human capital in policy formulation，we should enhance the social adaptation of migrants from multiple dimensions，improve the level of governance and services in resettlement communities，promote the social interactions of migrants，and enhance the identity of migrants’communities；we should strengthen the publicity and education of mental health in the community，improve the mental health literacy of migrants，and do a good job of providing psychological support；in the face of the livelihood and emotional impact of leaving the land，effective employment and income stabilization should be guaranteed as the basis of relocation support.