A method for eliminating CO in a restricted space through ultrasonic atomizing spray of a chemical absorbing solution belongs o a chemical absorption method of ultrasonic atomizing spray. An ultrasonic atomizing device is combined with the chemical absorption method to achieve the purpose of rapid and effective reduction of the concentration of CO in the restricted space. A CuCl/MgCl2 mixed solution for efficiently absorbing CO at normal temperature under normal pressure is selected, compressed air is used to impact a resonant cavity to generate ultrasonic waves in order to atomize the mixed solution into dense fine fog droplets with the diameter being 50 [mu] or less, and the fog droplets suspend in air for a long time to increase the solution and air contact area and guarantee the absorption efficiency of the chemical absorbing solution. The device can reduce the CO concentration to 20 ppm or less from 400 ppm within 20 min and keep the CO concentration below 20 ppm within 120 h. Thedevice has the advantages of mild application conditions, simplicity in storage, safety, non-toxicity, and meeting of needs of sustainable development. Additionally, the device also has the characteristics of simplicity in operation, low cost, lightness and portability, and provision of a good support for purifying gas in mine rescue capsules, refuge chambers, subway traffic and other restrictedspaces.