Abstract: According to the layout, condition of pebble foundation and character of permeability of Bhote Koshi hydroelectric project head works in Nepal, the optimal design plan of impermeable wall determined and grouting curtain was by analysis of sensitivity about the depth of concrete impermeable wall, the length of grouting curtain and the permeability of concrete and foundation, and also three dimensional seepage calculation under the conditions of three reservoir water levels was carried out. The result will provide the basic data for the optimal design.