For the project of the hazardous waste pollution emergency control in Jingjiang of Jiangsu Province, compared with rigid vertical seepage control block, flexible vertical block can better effects to block hydraulic relation between the landfill pollution and the surrounding soil and groundwater. Flexible vertical seepage control block has the characteristics of good impervious performance, strong anti-deformation ability and long service life. This article introduces the technical principle, construction technology and key points of construction of flexible vertical block.