Shyness, which is characterized by social withdrawal behaviours and approaching-withdrawal conflicted social motivations, is suggested to influence children's social-emotional development. This study examined the association between shyness and social-emotional development among Chinese children aged 3 to 12. A systematic search of both Chinese and international databases for relevant research between 1990 and 2020 yielded 23 studies (n = 9,009 children), which were systematically reviewed. Among them, 15 studies (n = 6,303 children) were included in the meta-analyses. Results from random-effects models indicated that shyness was positively associated with internalizing problems (r=0.21, p<0.01), externalizing problems (r=0.14, p<0.01), peer victimization (r=0.23, p<0.05), and asocial behaviours (r=0.47,p<0.05), and negatively associated with peer preference (r=-0.19, p<0.01) and school social competence (for school-aged children r=-0.19, p<0.01; for preschool children r=-0.22, p<0.01) in the Chinese context. Further, analyses revealed that the relationship between shyness and social-emotional development was moderated by children's characteristics (e.g., gender, age, receptive vocabulary, and emotional competence), social relationship (e.g., teacher-child relationship and parent-child attachment), and situational context (e.g., interpersonal similarity). This study suggests that shyness generally exerts negative influences on Chinese children's social-emotional development, but the influences are unique to particular social-emotional domains and moderated by both children's characteristics and environmental factors.