To discuss effects and mechanism of Ping Chuan formula and its different disassembled formulae on preventing and curing asthma.Methods:To establish the model of asthmatic mice, the BALB/c mice were sensitized by intra-peritioneal injection of mixed ovalbumin and then activated by inhaling ovalbumin. 120 BALB/c mice were randomly divided into 6 groups: the normal group, the asthma model group, the Ping Chuan formula group, CF 1 (Ping Chuan formula disassembled prescription 1 group), CF2, CF3. After the 7 days and 21 days of activated asthma, the lung cells were treated with Trizol for extraction of total RNA, the gene expression of T-bet,GATA-3 were analyzed by RT-PCR; the general histological changes of lung tissue were observed by hematoxylin and eosin stain.Results:At the 7th day, the expression of T-bet in CF1、CF2 and CF3 were obviously increased（P<0.05）；the expression of GATA-3 in Ping Chuan formula、 CF2 and CF3 were obviously decreasedP<0.01). The ratio of T-bet/GATA-3 in CF3 were higher than the other goupe (P<0.05).At the 21th day,the expression of T-bet were increased in every groupe（P<0.01），the expression of GATA-3 significantly decreased(P<0.01)，The ratio of T-bet/GATA-3 were increased (P<0.01).CF1 and CF2’s T-bet expression level were lower than Ping Chuan formula and CF3(P<0.05),GATA-3 were higher (P<0.01), and the ratio of T-bet/GATA-3 were lower than Ping Chuan formula and CF3 (P<0.05 orP<0.01).Conclusion:Ping Chuan formula and its different disassembled prescription can regulate the expression of T-bet/GATA-3 mRNA which are the upstream factors of Th1/Th2, then regulate the balance of Th1/Th2. CF3’s curative effect is nearly equal to the effect of Ping Chuan formula.