Objective：To investigate the effect of inhaling rapamycin on CD4+CD25+ regulatory T cells （Treg） ratio and the treatment of asthma，as well as its related mechanisms，using asthmatic mice treated with inhaled rapamycin therapy. Methods：A total of 30 cases of BALB/c mice were random divided into three groups：the control group，the model group，and the rapamycin treatment group，each group had 10 cases. Underwood method was performed to estimate mouse lung tissue scores. CD4+CD25+ Treg cell ratios of peripheral blood and lung tissues were detected by flow cytometry. Different concentrations（50 and 100 nmol/L） rapamycin were used to treat mice CD4+ T cells，and CD4+CD25+ Treg cell formation ratio and Foxp3 mRNA expression were analyzed by flow cytometry and RT-PCR methods. Results：Compared with the model group，rapamycin treatment significantly improved lung tissue pathology score. CD4+CD25+ Treg percentage in the model group was （1.94 ± 0.37）% and （2.74±0.42）% in peripheral blood mononuclear cells（PBMCs） and lung tissues，respectively，after rapamycin treatment，the CD4+CD25+ Treg percentage was（5.11±0.64）% and（2.74±0.42）% in PBMCs and lung tissues，respectively. After treated with different concentrations of rapamycin，CD4+CD25+ Treg ratio in the control group was（4.84 ± 0.76）%，and in the 50 nmol/L and the 100 nmol/L rapamycin groups was（7.47±1.84）% and（10.93±2.74）%，respectively. RT-PCR results were consistent with the results of flow cytometry staining，rapamycin treatment significantly promoted CD4 T cells Foxp3 expression （P<0.01）. Conclusion：By promoting CD4+CD25+ Treg cell proliferation，rapamycin can increase CD4+CD25+ Treg cell ratio of peripheral blood and lung tissues in asthmatic mice，and thus exert a therapeutic effect on asthma.