This paper presents some results of research into materials selection soil - bentonite - cement reasonable to enhance slurry wall for waterproofing of earth dams. The results showed that mixed C-S-B (cement - soil - bentonite) with reasonable rates will increase waterproofing than the original soil (seepage factor decreased from 10-4 cm/s down to range (1.9 - 15) 10 exponent 7 cm/s) , while in the presence of resistant cement mix cut of C-S-B roughly equivalent to the original soil sample fonns, creating as well between the trench walls and dams, increasing the stability of the dam. Mixed C-S-B has met the requirement water-proofing ability and resistance to cutting, and improve economic efficiency (cost of a block of material C-S-B decreased compared with C-B between 15 - 20 percent) due to damming of soil use.