Abstract: In order to explore the multifractal characteristics of the pore structure of coal under multistage pulse ultrasonic excitation and its impact on the desorption kinetic laws of gas, the ultrasonic excitation test system for gas-containing coal was employed to conduct the gas desorption test of water-saturated coal under multi-level pulse ultrasonic excitation. Coupled with low-pressure CO₂ adsorption, low-temperature N₂ adsorption, and high-pressure mercury intrusion tests, based on the multifractal theory, the multifractal characteristics of micropores (<2 nm), mesopores (2-50 nm), and macropores (>50 nm) of coal under multi-level pulse ultrasonic stimulation and their influence on the kinetics of gas desorption were studied. The results indicate that compared with the continuous ultrasonic excitation of coal, the pore volume and specific surface area of each pore diameter segment of coal under multi-level pulse ultrasonic excitation have all increased. The pore distribution of coal under multi-level pulse ultrasonic excitation exhibits multifractal characteristics. The multifractal singularity spectrum width ∆α of micropores ranges from 0.422 3 to 0.481 4, that of mesopores ranges from 0.485 7 to 0.574 2, and that of macropores ranges from 2.099 8 to 2.100 8. The multifractal difference D_min−D_max of micropores and mesopores in coal under ultrasonic excitation undergoes a significant change and shows a decreasing trend with the increase in the number of multi-level pulse ultrasonic waves, while the change in the multifractal difference D_min−D_max of macropores under ultrasonic excitation is not obvious. Compared with the Langmuir model and the pseudo-first-order kinetic model, the pseudo-second-order kinetic model can more accurately describe the kinetics of gas desorption from coal under ultrasonic excitation. With the increase in ultrasonic power and the number of multistage pulses, the multifractal spectrum parameter ∆α of micropores and mesopores of coal presents a downward trend, while the generalized fractal dimension D, the limit gas desorption amount Q_∞, the equilibrium constant b, and the desorption rate constants k₁ and k₂ all increase. Under the excitation of multilevel pulse ultrasonic waves, the uniformity of coal pores is improved, which leads to the increase of the ultimate desorption amount of gas Q_∞ and the desorption rate constant k₂ by 105.660% and 125.641% respectively compared with the excitation of non-pulse ultrasonic waves (200 W).Multi-level pulse ultrasonic waves activate the synergistic multi-scale transformation of coal pores and significantly enhance the geometric morphology, connectivity, and uniformity of micropores and mesopores of coal, influencing the strong adsorption sites of gas within micropores and mesopores, thereby promoting the desorption of gas in coal. Subsequently, issues such as the construction of a multi-scale gas desorption and diffusion model of coal under the action of ultrasonic waves can be further explored.