Abstract: The detonation propagation of active steam controlling gas explosion has been studied on a small-sized experimental installation with 88 mm in inner diameter and 1 600 mm in length.And character of flame propagation was monitored by high speed photographic instrument.Treated by high-power physical methods,common water can change into active water with small molecules group;the active water,whose diameter is half as that of com-mon water molecule,is composed of five to eight water molecules,then it witch to active steam after going through steam generator,functions as homogeneous-phase,equal-diameter inhibitor and nanometer-active controller during procedure of gas explosion.The result shows that when activation steam is injected into experimental pipe,induc-tion period and flame propagation time in the pipe of gas explosion was prolonged,and mean rate of flame propa-gation were reduced remarkably.The effect of controlling explosion of activation steam is high in comparison with that of common steam.