β-hydroxybutyric acid (β-HBA) is a water soluble small molecule and the main component of ketone body. Upon facing energy shortage, free fatty acids in liver are oxidized and decomposed in mitochondria to produce β-HBA. β-HBA is a carbon source providing energy for extrahepatic tissues such as brain, heart, and skeletal muscles. Intestinal flora is the key component of regulating the host lipid metabolism and other metabolic activities of human body. The imbalance of intestinal flora may lead to the disorders of fatty acid metabolism having impact on cardiovascular, nervous, metabolic systems, etc. This work discusses the potential regulatory mechanism of intestinal flora involved in producing β-HBA through metabolic pathway, molecular mechanism of β-HBA production, physiological effects in animals, and relation between intestinal flora and fatty acid metabolism. These outcomes can provide reference for further work on β-HBA production in treating diseases, especially for cancer treatment in terms of the energy metabolism.