Research conclusions: Usually, when the cutting subgrade passes through riverside with the excavation depth below the water flood level, the scheme of the watertight curtain should be chosen on consideration of the technological, economic and safe factors to reduce the influence of adverse factors on the new railway as much as possible. This is one of the ways to deal with the problems in such project. In the choice of the scheme, the misunderstanding of blindly seeking the low cost should be given up, and the high performance to price should be sought.