Objective:To study the neuroprotective effects and the mechanism of CoQ10 on Rotenone-induced dopaminergic neurons. Methods:Using Rotenone upon dopaminergic mesencephalic neurons in primary culture to set up cell model of Parkinson’s disease (PD) in vitro. The dopaminergic neurons were identified by tyrosine hydroxylase(TH) immunocytochemistry. A lactate dehydrogenase (LDH) assay kit was used to measure the transudatory amount of LDH to reflect the cell viability. By measuring the intracellular Rhodamine 123 fluorescene density,mitochondrial potential(△Ψm) was evaluated. Results:Rotenone can dramatically reduce the cell viability and Ψm(P < 0.05). The rate of cell viability of dopaminergic neurons in group 15 nmol/L and 30 nmol/L rotenone were increased,and the percentage of △Ψm in group with 15 nmol/L and 30 nmol/L rotenone were increased(P < 0.05) as compared with group without rotenone treatment; while pretreatment with 50 μmol/L and 100 μmol/L CoQ10 can significantly prevent 15 nmol/L Rotenone-induced dopaminergic neurons mitochondrial depolarization(P < 0.05). Conclusion:CoQ10 can effectively protect the rotenone-induced dopaminergic neurons.