Abstract: Layue tunnel is located on Sichuan-Tibet railway, it is prone to high geo-temperature induced heat haz? ards. So, hydrochemical and isotopic analysis is carried out for Changqing, Pailong and Layue hot springs, which are closely related to the tunnel. It is found that the above hot springs are formed by different causes and all mixed with cold water. Among the others, the mixing ratio of cold water in Layue hot spring is as high as 91%. Considering the effect of cold water mixing on the prediction of high geo-temperature induced heat hazards in the tunnel, two mixing modes of cold water in hot-spring are put forward. In the mixing mode of shallow cold water with hot water, the mixing zone of cold and hot water is generally close to or higher than the elevation of the hot spring point. So, the heat hazard risk induced by high geo-temperature would be greater when a tunnel is built below the elevation of the hot spring point. In the mixing mode of hot water and confined cold water, the mixing zone of cold and hot water is generally located in the confined cold water aquifer, lower than the elevation of the hot spring point. The heat hazard risk induced by high geo-temperature would be smaller when a tunnel is built above the elevation of the hot spring point.According to the landform, geological structure, hot springs, boreholes and other geological information, it is inferred that the hot springs in the studied area are the mixing mode of hot water and shallow cold water. Based on the above viewpoint, the high geo-temperature induced heat hazards are predicted for the Layue tunnel and it is determined that there are 6 sections with high geo-temperature induced heat hazard risks. Among them, the section ① ~ ④might have higher heat hazards, and section ⑥ should be further researched to determine the degree of the heat hazard.