The invention relates to a sterile medical ultrasonic coupling agent for a cavitary tract and a preparation method thereof. The sterile medical ultrasonic coupling agent is prepared from the following raw materials in parts by weight: 0.5 to 2 parts of carbomer, 0.05 to 0.3 part of vitamin E, 3 parts of oleum curcumae, 0.5 to 2.5 parts of antibacterial agent, 1 to 3.5 parts of triethanolamine, 10 to 22 parts of wetting agent and 200 to 300 parts of purified water. The preparation method of the sterile medical ultrasonic coupling agent comprises the following steps of uniformly dispersing the carbomer in the antibacterial agent and the wetting agent, afterwards, adding an obtained first mixture into 2/3 by weight of the purified water, agitating and swelling an obtained second mixture, adding the rest 1/3 by weight of the purified water into the second mixture, uniformly mixing an obtained third mixture, adding the vitamin E and the oleum curcumae into the third mixture, uniformly mixing an obtained fourth mixture, then adding the triethanolamine into the fourth mixture, uniformly mixing an obtained fifth mixture, afterwards, filling and sealing the fifth mixture, and carrying out cobalt-60 irradiation sterilization, so as to obtain the sterile medical ultrasonic coupling agent. The sterile medical ultrasonic coupling agent can meet antibacterial, sterile and acoustic-performance requirements, effectively prevents a cross infection, and meanwhile, has functions of nourishing the skin, restoring pathological tissue and promoting wound-surface healing.