Abstract: In order to ensure the security of Yuanliangshan tunnel construction and run, considered karst development, characteristics of water gushing and mud soil projecting and their influences of precipitation in the east flank of Tongmaling anticline, four harnessing projects are compared among tunnel drainage, horizontal heading tunnel drainage, plugging and blockage combined with drainage, and the first project is selected finally. Because of many storms occurred in the anticline area during the rain season in May to September, 2003, large scale water gushing and projecting(mixed with mud, sand and stone) took place frequently in some sections, epically in DK361+764 and DK360+873, but they were all drained and the tunnel and its lining structure are safe and sound. The fact indicates that it is the right choice to utilize the tunnel drainage project to harness the karst water gushing and mud projecting hazards in the east flank of Tongmaling anticline.