In this study, we found the increased expression of the DNA methylation modification enzymes, DNMT1 and DNMT3b, and the H3K27me3 modification enzyme, EZH2, in lung tissues of the BPD model group from 7 and 10 day, respectively, with similar results in AT2 cells. The gene discussed is DNMT3B; the disease is bronchopulmonary dysplasia.