LAUSR

Abstract Parent–grandparent coparenting has become a common phenomenon in urban China. However, limited research has assessed interpersonal relationships in parent–grandparent coparenting families. This study aimed to investigate the characteristics of interpersonal relationships and examine the mediating role of marital conflict in the association between the parent-grandparent co-parenting relationship and the parent-child relationship in Chinese urban families. Using cross-sectional data from a sample of 317 parent–grandparent coparenting families, we conducted a series of measures, from the perspectives of mothers and fathers of young children respectively, to assess the parent–grandparent coparenting relationship, marital conflict, and the parent–child relationship. Our findings indicated that interpersonal relationships were relatively harmonious in parent–grandparent coparenting families. There was no significant difference between the mother–grandparent and the father–grandparent coparenting relationship, and the mother-child relationship scored significantly higher than the father-child relationship. Structural equation modeling with a bootstrap resample of 5000 indicated that parents’ marital conflict mediated the associations between the mother–grandparent coparenting relationship and the parent–child relationship, which consists of the mother-child relationship and the father-child relationship. The mediating role of parents’ marital conflict between the father–grandparent coparenting relationship and the parent–child relationship (neither mother-child relationship nor father-child relationship) was not found. Results contribute to knowledge pertaining to characteristics of interpersonal relationships in the parent–grandparent coparenting families. These findings highlight the contribution of harmonious parent–grandparent coparenting relationship and lower marital conflict to the parent–child relationship.