Objective：To study the level of interleukin 19（IL-19）in peripheral blood of children with asthma and investigate its importance. Methods：Three groups were in the experiment：the acute onset group of asthma（21 patients）, the catabasis group of asthma（19 patients）, and health control group（22 cases ）.The level of IL-19 and IgE in peripheral blood was respectively determined with ELISA. The accurate number of EOS in peripheral blood was counted with cytoanalyze. Results：Compared with the children of control group, the levels of IL-19, IgE and the quantity of EOS in peripheral blood of the patients with Asthma were obvious higher（P < 0.01）.The level of IL-19 and the quantity EOS of the patients of acute attack group were higher than those of the patients of catabasis group（P < 0.05）, but there is no significant difference in the level of IgE between the two groups of asthma. Furthermore, the results of correlation analysis ｓｈｏｗｅｄ that the levels of IL-19 positively correlated to the level of IgE and the quantity of EOS respectively in blood（r = 0.837, P ＜ 0.01；r = 0.742, P ＜ 0.01）. Conclusion：The IL-19 level of the children with asthma was always higher than that of health children, and the ａｓｃｅｎｄｉｎｇ degree of the IL-19 level are different during various periods of asthma. It may be inferred that IL-19 can play an important role in the pathogenesis of asthma， and observing the change of the level of IL-19 can make for the clinical diagnosis and monitoring the pathogenetic condition of asthma.