Objectives To explore the prevalence of maltreatment and the combined effect of maltreatment and frequency of positive parent-child interaction on psychosocial well-being in young children in China. Study design A retrospective study was conducted in 2016 in a representative sample of 20 324 children aged 34 years who were newly enrolled in kindergartens in Shanghai, China. All data were collected through online platforms. Parents reported the maltreatment history of their children and completed the Strengths and Difficulties Questionnaire and the Chinese Parent-Child Interaction Scale. Results The prevalence of parent-reported child maltreatment in Shanghai was 2.70% (95% CI, 2.38-3.05). A history of maltreatment increased the risk of total difficulties (aOR, 2.36; 95% CI, 1.39-4.03) and prosocial problems (aOR, 2.31; 95% CI, 1.37-3.91). A high frequency of positive parent-child interaction had a moderating effect on the correlation between maltreatment and prosocial problems. Conclusions Maltreated children had an increased risk of developing psychosocial problems, particularly those with a low frequency of positive parent-child interactions. A higher frequency of positive parent-child interactions may be associated with fewer adverse outcomes in maltreated children.