Research conclusions: (1)The main innuence factor for the tunnel scheme is the Heilongtan karst runoff which drains as spring groups to Heilongtan at the foot of Xiangshan Mountain，north of the ancient city Lijiang．The spring water is mainly supplemented by atmosphere precipitation in about 121 km2 kant depression zone，including Jiuzihai，Lariguang and Hongshuitang areas．This karst run off zone is a relatively independent vein runoff with a small hydraulic gradient and low flowing velocity．(2)The principle of route selection for the tunnel：Based on the researches on the harm of karst water to the tunnel and the influence of the tunnel excavation on the kant water system，the tunnel route should keep away from water concentrating area like large—scale corrosion basin or depression etc．and upriver karst runoff zone close to the reehar舀ng area．The route in front of the tunnel line should be heightened，SO that the tunnel can pass safely through the kant safe area close to the drainage area．