〔Abstract〕 Objective To investigate the reversal effect and mechanism of cinobufagin(CBG) on cisplatin resistance in human ovarian cancer cells. Methods A2780 cell line and its cisplatin-resistant cell line A2780/DDP are common ovarian cancer cells in clinic, so these two cell lines were selected as the research objects. The cell viability was detected by cell Counting Kit-8(CCK-8) assay, and the cell proliferation ability was detected by plate cloning and 5-ethynyl-2′-deoxyuridine(EdU) assay. Hoechst staining was used to observe cell apoptosis. Cell scratch test and Transwell test were used to evaluate cell migration and invasion ability. Western blot and quantitativereverse transcription PCR(RT-qPCR) were used to detect the protein and mRNA expressions of phosphatidylinositol 3-kinase/protein kinase(PI3K/AKT) signaling pathway and epithelial-mesenchymal transition(EMT). Results Compared with A2780 cells, the drug resistance indexes of A2780/DDP cells were 5.636, 5.864, 5.695, respectively. After treatment of A2780/DDP cells with CBG(2, 4, 6 mg/ml), the reversal resistance indexes were 1.617, 2.570, 3.461, respectively. CBG treatment significantly increased the level of apoptosis and inhibited the proliferation, migration and invasion of the cells in a concentration-dependent manner(P<0.05).Western blot results showed that compared with A2780 cells, the relative ratio of P-PI3K/PI3K and P-AKT/AKT protein levels, as well as the protein expression of N-cadherin, Vimentin, and Snail were higher in the control group(A2780/DDP) cells, while the protein expression of E-cadherin was lower(tP-PI3K/PI3K=8.115,tP-AKT/AKT=17.62,tN-cadherin=6.126,tVimentin=4.001,tSnail=17.333,tE-cadherin=4.620,P<0.01); As the dose of CBG increased, the protein expression levels of P-PI3K, P-AKT, N-cadherin, Vimentin, and Snail in drug-resistant cells decreased, while the protein expression level of E-cadherin increased(F P - PI3K =268.5,F P - AKT =190.5,F N - cadherin =24.02,F Vimentin =57.65,F Snail =87.24,F E - cadherin =135.8,P<0.05). qRT-PCR results showed that with the increase of CBG concentration, the mRNA expression levels of PI3K, AKT, N-cadherin, Vimentin and Snail decreased, while the mRNA expression level of E-cadherin gradually increased(F PI3K =101.1,F AKT =558.3,F N - cadherin =86.97,F Vimentin =105.9,F Snail =85.71,F E - cadherin =80.96,P<0.01). Conclusion CBG can reverse cisplatin resistance of ovarian cancer A2780/DDP cell line, and its mechanism may be related to the regulation of PI3K/AKT signaling pathway and inhibition of EMT by CBG.