Abstract: The gas-dust coupled explosion accidents endanger the development of the coal industry.In order to further investigate the pressure law of coupled explosion of gas-coal dust in semi-closed vertical space, a semi-closed vertical pipeline system, which including explosive chamber and propagation pipeline and supporting equipment, was built.The pressure data was simultaneously collected from both explosion chamber and propagation pipeline.In the system, the coal dusts with four kinds of coal dust concentration, i.e.25, 50, 100 and 200 g/m³, and four dust particle sizes, i.e.45, 75, 106 and 150μm, were coupled with gas with 9% concentration to conduct a coupled explosion experiment.By combining the experimental data and theory, the variation law of the maximum explosion pressure and the maximum pressure increase rate in the explosion chamber and the propagation pipeline were compared and analyzed.Experimental results show that:① with the decrease of coal dust particle size, the increase rates of maximum explosion pressure and maximum pressure in explosion chamber and propagation pipeline increase gradually, and reach the maximum when the particle size is 45 μm.The increase rate of maximum explosion pressure in the explosion chamber is higher than that in the propagating pipeline.There is a linearly regression relationship between the maximum pressure increase rate and particle size in the explosion chamber.The maximum pressure increase rate in the propagating pipeline increases with the decrease of coal dust particle size.The magnitude is getting larger, no obvious linear relationship be founded.② With the increase of coal dust concentration, the maximum explosion pressure and maximum pressure increase rate in the explosion chamber and propagation pipeline first increase and then decrease.Before reaching the peak, the maximum explosion pressure and maximum pressure increase rate in the explosion chamber are higher than that in the propagation pipeline.③ When the gas concentration is less than 9.5%, there is an optimal coal dust concentration in gas-dust coupled explosion, the maximum explosion pressure can reach its peak value under this concentration.When the coal dust concentration exceeds the optimal concentration, the coal dust has a restraining effect on the coupled explosion.When the coal dust with a concentration of 50 g/m³ is involved, the maximum explosion pressure reaches the peak value, which is the optimal coal dust concentration.When the coal dust with a concentration of 200 g/m³ participates, the coal dust has obvious inhibition effect on the coupled explosion.