Abstract: In order to reduce the great threat of gas explosion to coal mine operators and coal safety mining, the law of explosion overpressure and impact gas velocity attenuation with the propagation distance of different volumes of gas-air mixed gas in roadway was deeply studied. Firstly, based on dimensional analysis and energy similarity law, a dimensionless formula for the attenuation of gas explosion overpressure and impact gas velocity with propagation distance is established, considering the factors affecting the attenuation of gas explosion overpressure and impact gas velocity with propagation distance. Secondly, by regression analysis of the experimental data in large roadway, the attenuation models of overpressure and impact airflow velocity and their relations are obtained. Finally, the attenuation model and relation are verified. The results show that the energy of gas mixture, the amount of gas accumulation, the distance of measuring point, the hydraulic diameter and the cross-sectional area of roadway are the main factors affecting the attenuation of overpressure and impact gas velocity. Both overpressure and impact gas velocity are positively correlated with the accumulation of mixed gas. The greater the initial overpressure and impact gas velocity, the faster the attenuation. The relative errors between the theoretical value and the test value of the attenuation model and the relative errors between the theoretical value and the test value of the relation are controlled at about 10%, and the overall consistency of the data is high, which verifies the reliability of the data, and can describe the law of gas explosion propagation more simply and intuitively, and realize the rapid calculation of overpressure and gas velocity.