Abstract: Objective To investigate the expression of circular RNA（circRNA） hsa＿BABAM1＿1 in the placenta of preeclampsia（PE） and to explore the effect of circRNA hsa＿BABAM1＿1 on the proliferation and apoptosis of human placental trophoblast cell line（HTR-8/SVneo）. Methods Placental tissue samples of normal parturients（n=22） and parturients with PE（n=22） were collected from the Department of Obstetrics and Gynecology, General Hospital of Ningxia Medical University from January to December 2020. The expression of circRNA hsa＿BABAM1＿1 in placental tissue of the two groups was detected by quantitative real-time polymerase chain reaction（qRT-PCR）. PE model was established by culturing HTR-8/SVneo cells under hypoxic conditions, and the expression of circRNA hsa＿BABAM1＿1 under different culture condition was detected by qRT-PCR. RNase R enzyme digestion experiment and actinomycin D treatment experiment were used to verify the stability of circRNA hsa＿BABAM1＿1. The localization of circRNA hsa＿BABAM1＿1 in HTR-8/SVneo cells was located by fluorescence in situ hybridization（FISH） and nuclear and cytoplasmic separation. Stable lentivirus cell lines with high expression of circRNA hsa＿BABAM1＿1 and control empty vector were constructed respectively and treated as follows: control, empty vector, overexpression of circRNA hsa＿BABAM1＿1, hypoxia, empty vector+hypoxia and overexpression of circRNA hsa＿BABAM1＿1+hypoxia. The changes in cell proliferation were evaluated by cell counting kit-8（CCK-8） and 5-ethynyl-2’-deoxyuridine（EdU） experiments, and the changes of apoptosis were detected by flow cytometry and Western-blot. The expression of miR-130b-5p in HTR-8/SVneo cells and placenta was detected by qRT-PCR, and the correlation between the expression of circRNA hsa＿BABAM1＿1 and miR-130b-5p was analyzed by Pearson correlation analysis. Results Compared with the control group, the expression of circRNA hsa＿BABAM1＿1 was significantly decreased in PE placenta tissues and HTR8/SVneo cells in hypoxia group（both P＜0.05）. circRNA hsa＿BABAM1＿1 was mainly localized and expressed in the cytoplasm of HTR-8/SVneo cells. Compared with the control group, the cell survival rate （61.17±1.50）% vs（100.00±3.10）%, q=12.95, P＜0.01 and percentage of EdU positive cells （25.33±0.88）% vs（37.33±0.89）%, q=9.62, P＜0.01 decreased, and apoptosis rate （11.01±0.29）% vs（4.33±0.31）%, q=23.89, P＜0.01 increased, the expression of apoptosis related proteins such as cleaved cysteinyl aspartate specific proteinase（caspase）-9, cleaved caspase-3, cleaved caspase-7 and B-cell lymphoma-2（Bcl-2） associated X protein（Bax） increased, while Bcl-2 decreased, and the expression of miR-130b-5p increased in the hypoxia group. Compared with the empty vector+hypoxia group, the cell survival rate （89.21±2.79）% vs（61.23±2.13）%, q=9.71, P＜0.01 and percentage of EdU positive cells （36.67±0.88）% vs（24.33±1.86）%, q=9.89, P＜0.01 increased, and apoptosis rate （6.86±0.26）% vs（11.74±0.12）%, q=17.67, P＜0.01 decreased, the expression of cleaved caspase-9, cleaved caspase-3, cleaved caspase-7 and Bax decreased, while Bcl-2 iccreased, and the expression of miR-130b-5p decreased in the overexpression of circRNA hsa＿BABAM1＿1+hypoxia group. Pearson correlation analysis showed that the expression of circRNA hsa＿BABAM1＿1 was negatively correlated with miR-130b-5p in placenta tissues（r=-0.44, P＜0.01）. Conclusions CircRNA hsa＿BABAM1＿1 is expressed in the placenta and HTR-8/SVneo cells, mainly located in the cytoplasm and highly stable. Up-regulation of circRNA hsa＿BABAM1＿1 can promote proliferation and inhibit apoptosis of HTR-8/SVneo cells. The mechanism may be related to the regulation of miR-130b-5p expression.