Abstract: It is a engineering technological problem internationally for seepage treatment for underwater concrete of hydraulic structures and other else. In this paper the underwater LW chemical material grouting and the construction technique of SR anti-seepage module sticking are introduced for which it is used to treatment the transverse joints upstream at the dam block No. 19~20 in Xin’anjiang hydropower station. In addition, the author in this article discusses the new techniques which combine new anti-seepage underwater material with hydraulic technology in underwater construction．This new technique successfully carried out underwater anti-seepage treatment for transverse joints upstream under water 38.2 m.