Objective To clarify the protective effect of allopregnanolone (APα) on cell line SH-SY5Y damaged by 6-hydroxydopamine (6-OHDA) and its possible molecular mechanism.   Methods  6-OHDA, APα, γ-aminobutyric acid A receptor(GABAAR) antagonist, voltage-gated L-type Ca²⁺ channel antagonist were added to the in vitro cultured cell line SH-SY5Y. Immunofluorescence cell chemical staining was used to observe the changes of tyrosine hydroxylase (TH)-positive cells. The changes of the expression of calmodulin (CaM), Ca2+/calmodulin-dependent protein kinase Ⅱ δ3 (CaMKⅡδ3) in the cytoplasm and CaMKⅡδ3, brain derived neurotrophic factor (BDNF) and cyclin-dependent kinases 1(CDK1) in the nucleus of different groups were detected by Western blotting. The interaction between CaMKⅡδ3 and CDK1/BDNF was verified by co-precipitation.   Results  Having treated with APα, the number of TH and 5-Bromo-2-deoxyuridine (BrdU)-positive cells in 6-OHDA-lesioned SH-SY5Y cells increased significantly, but the number of TH/BrdU-double positive cells did not alter significantly. In the cytoplasmic or nucleus fraction of SH-SY5Y cells, the expression of the aforementioned proteins in the APα+6-OHDA group was higher than that in 6-OHDA+DMSO group by Western blotting, in particular, it increased significantly in APα+Bic+6-OHDA group compared with the APα+6-OHDA group. Immunoprecipitation assay showed that there existed an interaction between CaMKⅡδ3 and CDK1 or BDNF.   Conclusion  In the neuroprotective effect of APα on 6-OHDA-lesioned SH-SY5Y cells, GABAAR plays a negative regulation. As a result, APα increases the number of TH-positive neurons by stabilizing the cellular inner environment, in which the Ca²⁺ -CaM-CaMKⅡδ3 signaling pathway and BDNF, CDK1 plays a key role.