In Early Childhood Education and Care (ECEC) programs, the quality of teacher-child interactions is regarded to be important for children's vocabulary development. However, prior studies on the relationships between teacher and child, as measured by the Classroom Assessment Scoring System (CLASS), and children's vocabulary skills are inconsistent. In this study, we conducted a three-level meta-analysis to investigate the correlation between three CLASS domains and preschool children's vocabulary skills and then explored the moderating effects of vocabulary components, family SES, publication year, and sample mean age. Relevant literature was searched using four databases (Web of Science, PsycINFO, PsycARTICLES, ERIC) and Google Scholar, leading to the identification of 23 articles published between 2010 and 2022 meeting the inclusion criteria. The findings indicated that the overall effect of the associations between "Emotional Support," "Classroom Organization," "Instructional Support," and vocabulary skills was small to moderate in magnitude. Sensitivity and meta-bias analyses generally supported the robustness of the pooled effect of the association between three CLASS domains and children's vocabulary skills. Also, the association between "Emotional Support" and vocabulary skills was moderated by SES, and the components of vocabulary skills, while "Classroom Organization" and "Instructional Support" were only moderated by the components of vocabulary skills. Implications for future research on assessing the quality of early childhood education are discussed.