The invention discloses an oral liquid containing cinnamon, processed aconite root and prepared rehmannia root. A preparation method of the oral liquid comprises the following steps of: respectively uniformly mixing prepared rehmannia root powder, wine-prepared cornus powder and tree peony bark powder with a mixture of water, cane sugar and rice bran; sterilizing; cooling; inoculating a leaveningagent; fermenting and drying to obtain fermented prepared rehmannia root, fermented wine-prepared cornus and fermented tree peony bark; crushing cinnamon and fermented tree peony bark, and carrying out supercritical carbon dioxide extraction to obtain volatile oil and decoction dregs A; adding an ethanol solution into the fermented wine-prepared cornus, carrying out reflux extraction, and filtering to obtain filtrate A and decoction dregs B; crushing Chinese yam and poria cocos, adding water, and carrying out reflux extraction to obtain filtrate B and decoction dregs C; crushing processed aconite root, rhizoma alismatis, decoction dregs A, decoction dregs B, decoction dregs C and fermented prepared rehmannia root, adding ethanol for soaking, and sequentially carrying out ultrasonic and high-voltage pulsed electric field extraction to obtain filtrate C and decoction dregs D; adding water into the decoction dregs D, and decocting to obtain filtrate D; and mixing the filtrates with the volatile oil, concentrating, adding ethanol, standing, filtering, recovering ethanol, refrigerating, filtering, adding auxiliary materials, uniformly stirring, adding water, and uniformly stirring.