The invention provides an efficient injection method for a dustfall agent of a low-permeability coal seam. The efficient injection method comprises the following steps that 1, mechanical properties ofa coal body are measured; 2, the highest gas injection pressure of gas injection of high-pressure gas is determined; 3, drilling of the coal body is conducted; 4, decoupling charge is conducted; 5, high-pressure pipelines are reserved in drilled holes; 6, the drilled holes are sealed; 7, gas injection of the high-pressure gas is conducted; 8, explosive is detonated to conduct presplitting permeability-increasing; and 9, the dustfall agent is injected. The efficient injection method has the beneficial effects that construction is safe and reliable, the drilled holes are reasonably formed in ato-be-mined coal seam, the high-pressure gas (mixture gas of hydrogen and air) is injected, detonation synergy of the hydrogen and the explosive is achieved, the porosity of the to-be-mined coal seamis greatly increased, and presplitting permeability-increasing is large in radius and good in effect, so that the radius of dustfall agent injection of the low-permeability coal seam is increased, andthe injection effect of the dustfall agent of the low-permeability coal seam is greatly improved.