In this study, the generalized additive modeling (GAM) was used to explore possible threshold effects on multiple program structure quality indicators (class size, child-to-teacher ratio, teaching experience, teacher salary) in relation to the classroom teacher-child interaction quality indicators as measured by the Classroom Assessment Scoring System (CLASS) in a sample of Chinese kindergarten classrooms. One hundred eighty classrooms in 60 preschools were selected for the study, based on a stratified sampling procedure. The results were mixed, and revealed threshold effects on some structural indicators. The findings are discussed in the context of Chinese early childhood education practice. As the first study of its kind in a Chinese context, the findings could have some implications for early childhood education policy and practice despite some limitations of the study. Future research may consider better design and more representative sample for studying these issues.