The invention relates to a preparation technique of an inorganic membrane, in particular relates to a method for preparing a high-efficiency gas separation chabazite membrane, and belongs to the chemical separation field of environment, climate change, energy saving and emission reduction and the like. The method comprises the following steps: (1) membrane synthesis liquid preparation, to be more specific, mixing a strong alkali and a high silicon industrial raw m according to the mass ratio of aterial according to the mass ratio of 0.5 to 3:1, calcining at 400-650 DEG C for 0.5-5h, cooling and grinding to obtain a clinker, adding water into the clinker according to the liquid-to-solid mass ratio of 2-20:1, and stirring to obtain the membrane synthesis solution; and (2) membrane preparation, to be more specific, sealing two ends of a carrier tube coated with a chabazite crystal seed layer, putting the carrier tube with sealed two ends into a high pressure reactor, putting the membrane synthesis solution into the high pressure reactor for crystallization for 1-15 days at temperature of 60 to 110 DEG C, after the end of the reaction, taking a membrane tube, washing the membrane tube with deionized water to neutral, and drying to obtain the chabazite membrane. The preparation process of the chabazite membrane is simple, the cost is low, the chabazite membrane has high gas selectivity, and the chabazite membrane can efficiently separate flue gas, coalbed gas and other gases, and has extensive economic benefits.