Safety issues are of particular importance in low-concentration gas delivery. The gas explosion propagation rule and the effects of an active powder-spraying explosion-suppression device on a gas explosion in a pipeline were experimentally studied by using an experimental system with 43500 mm pipeline explosion suppression. The research demonstrates the gas explosion pressure and flame propagation law that were obtained in the 500-mm pipe. In combination with the action time of the active powder-spraying explosion-suppression device, its installation position in the gas transmission pipeline was determined. The active powder-spraying explosion suppression device exhibits a clear inhibitory effect on the flame and explosion pressure of a gas explosion in the pipeline, and the inhibitory effect varies with the amount of suppressant used. Under experimental conditions, a 10-kg explosion-suppression agent can successfully suppress the explosion flame, while the explosion pressure will be greatly attenuated. The conclusions provide an important theoretical basis for effectively suppressing a gas explosion in the low-concentration gas transportation process.