Aims: TCM practitioners usually compose prescriptions made up of Qiinvigorating herbal medicines (QIHM) or Qi-flow regulating herbal medicines (QRHM) for Qi system diseases, and have accumulated abundant clinical experience for a long time. To approach to the nature of Qi in TCM from bioenergetics, the effects of QIHM (ginseng, astragalus root, pilose asiabell root, white atractylodes rhizome) and QRHM (immature bitter orange, magnolia bark, green tangerine and lindera root) on oxidative phosphorylation (OXPHOS), bioenergy level and creatine kinase activities were investigated. Methods: QIHM and QRHM were administered by oral gavage daily for 10 days. Mice liver mitochondria were isolated by differential centrifugation. The effects of QIHM and QRHM on energy metabolism were studied from the production, regulation, and storage of bioenergy. Mitochondrial OXPHOS curve was determined by Clark oxygen electrode method. The levels of adenosine triphosphate (ATP), adenosine diphosphate (ADP) and adenosine monophosphate (AMP) in liver cells were determined by reversed-phase high performance liquid chromatography (RP-HPLC), adenylate energy charge (AEC), total adenylate pool (TAP) were calculated. The creatine kinase (CK) activities in mice skeletal muscle were determined by a commercial monitoring kit. The regularity of action of QIHM and QRHM were analyzed and concluded. Results: Ginseng and astragalus root can decrease oxygen consuming rate and respiratory control ratio (RCR) of liver mitochondria obviously, we consider this is appearance of lowering standard metabolic rate and is a kind of protective adaptation. QRHM can increase P/O ratio and RCR. Both QIHM and QRHM can stimulate activity of CK significantly in the storage of energy, and QRHM is stronger than QIHM. But it is worth notice that all the four QIHM can increase levels of ATP, AEC and TAP; on the contrary, all the four QRHM can decrease levels of ATP, AEC and TAP in liver cells. In a word, QIHM and QRHM increase and decrease bioenergy level of liver cells respectively in vivo. Therefore, Qi is closely related to bioenergy. Conclusion: Qi and bioenergy have common sources and identical functions. QIHM and QRHM are able to improve and decrease the energy state of the body respectively. Qi and bioenergy have general characteristics in many aspects. The experiments provide scientific evidence for Qi in TCM is bioenergy.