Abstract: OBJECTIVE To analyze the expression of 4 miRNAs（miR-99 a, miR-30 b, miR-126, miR-26 a） in peripheral blood of patients with acute respiratory distress syndrome（ARDS） caused by pulmonary infection and their predictive value. METHODS Eighty patients with pulmonary infection combined with ARDS who were hospitalized in Tianjin Fifth Central Hospital from Jan. 2017 to Dec. 2019 were recruited as the observation group; another 80 pulmonary infection patients without ARDS were enrolled as the control group. Real-time fluorescence quantitative polymerase chain reaction was used to detect the miRNA expression level, and clinical data of the two groups were collected. RESULTS The proportion of smoking, relative expression levels of miR-99 a and miR-30 b in the observation was significantly higher than that in the control group（P＜0.05）. Multivariate logistic regression analysis showed that smoking, miR-99 a and miR-30 b were the independent risk factors of ARDS in patients with pulmonary infection（P＜0.05）, and levels of miR-126 and miR-26 a were independent protective factors（P＜0.05）. ROC curve analysis showed that, the area under the curve of the combined detection of the four miRNAs were 0.897, the sensitivity was 74.0%, and the specificity was 91.7%, which was significantly higher than that of single detection. CONCLUSION MiR-99 a, miR-30 b, miR-126 and miR-26 a in peripheral blood can be used as potential biomarkers for early diagnosis of ARDS caused by pulmonary infection.