The invention discloses a formula of a coal-bed gas extraction drilling-sealing material and a preparation method thereof, and belongs to the technical field of coal-bed gas treatment, wherein the material comprises the following components by mass percent: 70%-75% of common silicate cement, 10%-15% of calcium sulfoaluminate cement clinker, 5%-10% of gypsum, 3%-5% of quick lime, 2% of bentonite, 0.4%-0.8% of foaming agent, 0.2%-0.6% of caustic soda; and the above components are mixed with water for use, and a water cement ratio is 0.75-0.85. The material disclosed by the invention has an expansion coefficient greater than 10%, uniaxial compressive strength greater than 10Mpa, better fluidity, short setting time, and safety reaching requirements of a mining hole-sealing material, so that sealing effect and gas drainage efficiency for coal-bed gas extraction drilling are improved, and number of drill holes is reduced; and meanwhile, in the formula disclosed by the invention, the cement is taken as the main material, so that production cost is saved.