Background and Purpose: Mitochondrial dysfunction leads to degeneration of dopamine (DA) neurons. Previous studies have showed that mitochondrial NAD+-dependent acetylase Sirtuin 3 (SIRT3) is downregulated in aging-related neurodegenerative disorders. Here, we determined the effect of downregulation of SIRT3 on acetylation of mitochondrial complex II (succinate dehydrogenase) subunit A (SDHA) and explored whether SIRT3 activating agents would rescue complex II activity and improve mitochondrial bioenergetics in PD models. Experimental Approach: SD rats and differentiated MN9D cells were treated with rotenone (ROT) to establish animal and cellular PD models. SIRT3 activators including icariin (ICA) and honokiol (HNK) were employed to activate SIRT3 in the PD models. Protein acetylation was detected using western blot and immunoprecipitation. Activities of SIRT3 and mitochondrial Complex II, NAD/NADH ratio, mitochondrial respiration and ATP production were assessed in different models. Key Results: SIRT3 activity was suppressed in ROT-induced PD models. The downregulation of SIRT3 resulted in hyperacetylation of SDHA, leading to compromised activity of mitochondrial complex II and a decline in ATP production. Mechanistically, the suppression of SIRT3 activity was attributed to the decrease of NAD+/NADH ratio caused by the inhibition of mitochondrial complex I induced by ROT. Activation of SIRT3 by ICA and HNK improved complex II activity and elevated the production of ATP, resulting in protection against ROT-induced injuries to DA neurons. Conclusion and Implications: These findings reveal an unrecognized regulatory SIRT3-SDHA axis, and improving bioenergy deficiency through SIRT3 activation dependent rescue of mitochondrial complex II activity may provide an effective strategy for protecting neuronal degeneration.