The invention relates to a disinfecting and sterilizing medical ultrasonic coupling agent with moisturizing and skin-moistening effects and a preparation method of the disinfecting and sterilizing medical ultrasonic coupling agent. The coupling agent comprises the following raw materials in percentage by weight: 0.1%-0.5% of polyhexamethylene guanidine, 1%-4% of cationic chitosan, 1%-8% of a cationic polymer, 0.4%-1.5% of allantoin polyaluminum chloride, 0.1%-0.5% of water-soluble vitamin E, 5%-20% of glycerin and the balance of distilled water. The preparation technology comprises the following steps: measuring distilled water and glycerin, stirring and mixing evenly, heating to 100 DEG C; when cooling water to 60-70 DEG C, adding polyhexamethylene guanidine, cationic chitosan, cationic polymer, allantoin polyaluminum chloride and water-soluble vitamin E under agitation; and further slowly stirring for 30-60 minutes, standing for 24 hours, filling and packaging. The medical ultrasonic coupling agent prepared by the method has the advantages of fast disinfecting and sterilizing effects, no corrosion on an ultrasonic probe, few bubbles (clear image), excellent biocompatibility and high lubricating property, and has moisturizing and skin-moistening efficacies; meanwhile, the preparation technology is simple and environmentally friendly; large-scale production is easy to realize; and the cost is low.