Research Question: The precise mechanism by which estrogen facilitates the progression of adenomyosis remains uncertain.Design: Fluorescence in situ hybridization was used to observe the expression pattern of miR-145 in adenomyosis ectopic endometrium (nAc=13), adenomyosis eutopic endometrium (nAu=15) and non-adenomyosis eutopic endometrium (nnAu=14). RNA sequencing was used to screen target genes as well as downstream pathways of miR-145, which were validated by reporter gene assay, qPCR and western blot, and further analyzed using cell function assay and chromatin immunoprecipitation assay.Results: The fluorescence in situ hybridization assay revealed a noteworthy elevation in miR-145 expression in adenomyosis tissue compared to non-adenomyosis tissue. Furthermore, RNA sequencing analysis revealed that overexpression of miR-145 resulted in heightened expression of genes associated with the cytokine signaling pathway, NOD-like pathway, and adhesion pathway, including IL-1β and IL-6. Besides, our study has identified CITED2 as a downstream direct target gene of miR-145, which is implicated in the inhibition of stromal cell migration induced by miR-145. Moreover, chromatin immunoprecipitation was employed to validate the direct impact of estradiol on the promoter region of miR-145, mediated by estrogen receptor α, which facilitates the upregulation of miR-145 expression.Conclusion: Our findings provide evidence supporting the role of estradiol, acting through its receptor α, in modulating the miR-145-CITED2 signaling axis, thereby promoting the progression of adenomyosis.