Objective To investigate the effect of IL-19 on airway smooth muscle cells ( ASMCs) proliferation in asthmatic rats． Methods The rat model of asthma was made through ovalbumin ( OVA) sensitization and excitation． Primary cultures of ASMCs were established for experiments． ASMCs were treated with 1 μg /L、10 μg /L 、100 μg /L IL- 19． Adopt flow cytometry and MTT method to detect the proliferation of ASMCs，and observe the influence of different concentrations of IL-19 on the proliferation of ASMCs． Results Compared with normal rats，the proliferation of ASMCs in chronic asthmatic rats and the percentage of cells at S phase was obvious increased． The percentage of cells at S phase of ASMCs in chronic asthmatic rats intervened by 10 μg /L、100 μg /L IL-19 was decreased and the proliferation of ASMCs was reduced compared with the asthmatic group，and there is difference between 10 μg /L IL-19 group and 100 μg /L IL-19 group． But these two indexes of ASMCs in chronic asthmatic rats have no obvious change after intervening by 1 μg /L IL-19． Conclusion L-19 may inhibit the proliferation of ASMCs in chronic asthmatic rats．