Abstract: In order to explore the influence of mechanical vibration on the gas diffusion characteristics of granular coal, the self-developed vibration-gas adsorption-desorption experimental platform was used to conduct the gas desorption-diffusion experiments of coal samples with different particle sizes before and after vibration. The dynamic diffusion coefficient model was used to select the lean coal of 1-3 mm and 0.25-0.3 mm in Guishuting Mine, respectively. The gas desorption-diffusion experiment of coal samples was carried out, and the vibration of coal samples with different particle sizes before and after was compared. The results show that the application of vibration can increase the gas diffusion amount and diffusion speed of granular coal, and the initial effective diffusion coefficient of gas desorption is also improved. The initial effective diffusion coefficient of small particle size coal sample is smaller than that of large particle size coal sample, but the early diffusion rate is larger, and the vibration has a greater impact on the diffusion characteristics. It is pointed out that, on the one hand, the enhancement of vibration effect of small-size coal samples leads to more obvious external force generated by vibration, which further aggravates the degree of gas diffusion. On the other hand, coal samples with large particle size have larger surface area, and can absorb more gas than coal samples with small particle size, so the initial diffusion rate is larger.