Pingchuan Formula (PCF) is a traditional Chinese recipe. PCF improves chronic airway inflammation by correcting the imbalance of T-helper cell ratio. The purpose of this study was to investigate the effect of PCF on pathological changes in the lungs of asthmatic mice in terms of Treg/Th17 balance. A bronchial asthma BALB/c mouse model was established using the ovalbumin excitation method. Distilled water (for MDL group) and drugs (for DEX or PCF group) were administered by gavage immediately after the first excitation. Mice were sacrificed after 7 and 28 d treatment. Lung tissues and bronchoalveolar lavage fluid were collected and lung pathological changes were observed after hematoxylin and eosin staining. Differential cell counts, concentrations of interleukins-6, -17, -23 and TGF-β in bronchoalveolar lavage fluid were determined by enzyme-linked immunosorbent assay. Expression of transcriptional factors Foxp3 and RORγt was determined by immunohistochemistry and immunoblot. An asthma model was successfully established. After 7 or 28 d treatment, lung pathological changes were improved and concentration of interleukins-6, -17, -23 and TGF-β in bronchoalveolar lavage fluid significantly decreased in the PCF group. RORγt expression in lung tissue was decreased in the PCF group, while Foxp3 expression increased (all P values < 0.05 compared with the MDL group). There was no significant difference between the PCF and DEX group except that mice in the PCF group lost less bodyweight. Treatment with PCF downregulates RORγt, elevates Foxp3 expression, reduces interleukins-6, -17, -23 and TGF-β in bronchoalveolar lavage fluid, thus restoring Th17/Treg balance, improving airway inflammation and reducing asthma symptoms.