In this study, we detected the expressions of miR‐29b, B7‐H3 and STAT3 in the peripheral blood mononuclear of children with asthma, and confirmed through in vitro experiments and animal models that miR‐29b participated in the immune inflammatory response of asthma by reducing Th2 cell differentiation through inhibiting B7‐H3 and STAT3. This evidence concerns the gene STAT3 and asthma.