Abstract: Objective　To identify the differentially expressed microRNAs（miRNA）in plasma of Mycoplasma pneumoniae pneumonia (MPP) by miRNA microarray. Methods　36 cases of hospitalized children with MPP were enrolled (MPP group). 27 cases of healthy children were enrolled as control group (NC group) in the same period. Microarray chip was used to find out differentially expressed miRNAs of plasma from 3 cases with MPP group and 3 cases with NC group.  Real-time quantitative PCR was chosen to detect the expression of miR-222-3p and miR-492 in leukocytes from MPP group (n=36) and NC group (n=27).  Results　26 miRNAs differentially expressed between the two groups were screened out by miRNA microarray assays, of which the expression of 19 miRNAs was elevated, while 7 miRNAs declined. Compared with NC group, the expression of miR-222-3p and miR-492 increased in the MPP group (P＜0.01).  Conclusions　Some miRNAs are differently expressed in peripheral blood of MPP patients, which may be involved in the immunopathogenesis of MPP. Key