Abstract: Objective To explore the expression of miR-363-3 p in eutopic endometria(Eu)and ectopic endometria(Ec),and explore their impacts on the biological behaviors of endometrial stroma cells(EnSCs). Methods The eutopic(n=30)and ectopic(n=37)endometria from 30 women with endometriosis who underwent laparoscopic surgical procedures in our hospital from October 2017 to October 2018 with age ranging from 24 to 48 years were collected.Real time quantitative PCR was used to detect the expression of miR-363-3 p in these tissues.EnSCs were transfected with the miR-363-3 p mimics and negative control.After transfection,apoptosis marker caspase3,proliferation,Ki-67 and invasive makers MMP-2,MMP-9 were measured and CCK8,flow cytometry assay were used to evaluate cell proliferation and apoptosis. Results Compared to Eu,the levels of miR-363-3 p was significantly lower in Ec(P<0.001).Compared with the negative control,overexpression of miR-363-3 p was seen in EnSCs.After overexpression of miR-363-3 p in EnSCs,Caspase3 increased(P=0.01),Ki-67 decreased(P<0.001),while MMP-2,MMP-9 did not remarkably change(P>0.05).However,the apoptosis rate significantly increased(P<0.001)and proliferation rate reduced(P<0.001). Conclusion Downregulation of miR-363-3 p in Ec lesions increased of endomereiosis may promote cell proliferation and result in the occurrence of endometriosis.