Before performing colonoscopy, 30-50 ml of dimethylsiloxane oil (bulk) can be taken 3-4 hours in advance, prepared at a concentration of 0.5% to 1.0%, and injected through the colonoscopy orifice during the operation if necessary. Dimethylsiloxane Oil (Bulk) is an anti-foaming agent, which can change the surface tension of air bubbles and eliminate the foam in the gastrointestinal tract, thus improving the clarity of gastroscopy and radiography. It is suitable for use as an adjunct to gastroscopy and radiography, and can also be used clinically for colonoscopy and other examinations. Freshly configured 0.5%-1.0% dimethylsiloxane oil bulk aqueous suspension 30-50 ml can be taken orally within 3-4 hours before performing colonoscopy.In addition, if foamy mucus is still found in the field of view during endoscopy, the drug can be injected through the orifice substance. Contraindications to the use of the drug include hypersensitivity to the product. There are no known adverse reactions to the use of the drug. Specific use of the drug should be carried out under the guidance of a specialist.