Social avoidance has been found to be related to negative social adjustment, yet evidence of the relationship between social avoidance and social adjustment is very limited in suburban preschoolers in China. Moreover, the underlying mechanisms that help to explain the associations between social avoidance and socio-emotional adjustment remain poorly considered. The goal of the present study was to examine the moderating effect of marital conflict in the link between social avoidance and indices of socio-emotional functioning among young children in mainland China. Participants were 256 children aged from 49 to 72 months (125 boys, 131 girls,  = 59.06 months,  = 6.58) attending preschools/kindergartens in suburban areas of Shanghai, People's Republic of China. Multi-source assessments were employed, with mothers reporting marital conflict as well as rating their children's social withdrawal (i.e., social avoidance, shyness, unsociability), and teachers assessing indices of children's socio-emotional functioning at school (i.e., anxious-fearful behavior, peer exclusion, and loneliness). Children were asked about their loneliness. Among the results, social avoidance was positively associated with anxious-fearful behavior, peer exclusion, and loneliness (marginal significance). Moreover, as hypothesized, marital conflict was found to exacerbate the relations between social avoidance and peer exclusion, and loneliness. Results are discussed in terms of the etiology and implications of social avoidance among young children in mainland China.