BackgroundMigrant children face many challenges in the process of social change and adaptation to a new environment， especially in school adaptation. Studies have shown that peer attachment plays a vital role in the social adaptation of children and adolescents， while psychological resilience and sense of security， as important psychological resources， also play a moderating and mediating role in individuals' coping with environmental changes. However， there is a lack of systematic research on how peer attachment affects the school adaptation of migrant children through psychological resilience and whether this process is moderated by sense of security. ObjectiveTo explore the relationship between peer attachment and school adaptation of migrant children and to examine the path of psychological resilience and sense of security in it， so as to provide references for improving the school adaptation of migrant children. MethodsUsing cluster sampling method， 695 migrant children in grades 4 to 6 of a primary school in an urban-rural fringe area of Sichuan Province were selected from April 1 to 30， 2022. Assessments were conducted using Revised Inventory for Parent and Peer Attachment （IPPA-R）， Resilience Scale for Chinese Adolescents （RSCA）， Scale of Sense of Security of Children Left Behind （SSSCLB） and Scale of School Adjustment of Student （SSAS）. Process 4.1 was used to examine the role of psychological resilience and sense of security. ResultsA total of 631 （90.79%） valid questionnaires were gathered. There were significant positive correlations among IPPA-R peer attachment subscale score， RSCA score， SSSCLB score and SSAS score （r=0.160~0.600， P<0.01）. Peer attachment had a significant positive predictive effect on the school adaptation （β=0.178， P<0.01） and psychological resilience （β=0.518， P<0.01） of migrant children. Psychological resilience had positive predictive effect on the school adaptation （β=0.467， P<0.01）. Psychological resilience played a partial mediating role in the relationship between peer attachment and school adaptation， with the mediating effect value was 0.242 （95% CI： 0.184~0.302）， accounting for 57.62% of the total effect. Moreover， the interaction term between psychological resilience and sense of security had a significant predictive effect on school adaptation （β=0.103， P<0.01）. ConclusionThe psychological resilience of migrant children plays a partial mediating role in the relationship between peer attachment and school adaptation， and the status of sense of security can moderate the relationship between psychological resilience and school adaptation of migrant children.