The invention provides a method for preparing coal mine gas instant eliminating liquid and a method for using the coal mine gas instant eliminating liquid. The coal mine gas instant eliminating liquid is prepared from the following components, by weight, 33-46% of beer, 31-41% of acetic acid, 16-22% of vegetable protein, 8-13% of cane sugar, 6-9% of apple green agents, 5-11% of alums and 4-13% of sodium carbonate. The sum of the ratios of the components by weight is 100%. The conception of passive prevention and treatment in the prior art is completely changed, the methods belong to the category of active prevention and treatment, basically, gas is treated before coal is mined, drilling can be conducted on the ground when mine construction is conducted, the gas eliminating liquid can effectively decompose coal mine gas when a coal bed is in the initial condition, therefore, the concentration of the coal mine gas is reduced, gas is treated to be within a safety range, and personal safety of digging workers is guaranteed.