Abstract: In order to analyze the reason of crazing of the coal-gas gravity dust catching ripple pipe of the large blast furnace,by optical microscope,scanned electrical microscope and electron energy spectrum,the angle of microcosmic structure,the shape of the zone of fracture and the component of the corrosion production were analyzed. The result showed that,the real reason was the stress and corrosion. And two improved measures were brought forward. One was improving the wave shape parameters so as to prolong the fatigue life-span,The other was advancing the ripple pipe′s capability through improving the material of the ripple pipe.