A preparation method of traditional Chinese medicinal oral liquid for treating tourette syndrome of children includes performing reflux extraction on radix paeoniae alba, bombyx batryticatus, gastrodia elata, uncaria rhynchophylla, radix curcumae, pheretima and buthus martensii, filtering, recovering ethanol, concentrating, adding distilled water, standing, and refrigerating; mixing rehmannia glutinosa libosch and the medicinal residue, decocting in water, filtering, concentrating, adding ethanol, standing, collecting supernatant, and filtering to obtain water extraction/ethanol precipitation liquid; mixing water extraction/ethanol precipitation liquid and ethanol extraction/water precipitation liquid, recovering ethanol, heating, concentrating, standing, filtering to obtain filtrate; mixing 1/3 volume of the filtrate with steviosin, stirring, mixing with the rest 2/3 of the filtrate, adding ethylparaben, adding water, regulating pH value, and standing; and centrifuging, collecting supernatant, adding water to regulate total volume to 1,000 mL, stirring, subpackaging, and sterilizing. Through improvement on the basis of the original process, the preparation method provided by the invention improves preparation appearance, solves the problems of poor clarity and stability in the original process, and ensures safety and efficacy of medicament in children.