The utility model discloses a prefabricated excrement ditch of " V " shape assembled, including prefabricated excrement ditch bottom surface and two excrement groove wall, excrement ditch bottom surface be " V " the shape two planes, just two planar contained angles are less than 180, the vertical setting of excrement groove wall and lie in two edges of excrement ditch bottom surface. This prefabricated excrement ditch of " V " shape assembled's efficiency of construction is high, and construction quality is controllable, and construction pollution is little, green energy -conservation.