Abstract: Geothermal resources is one kind of clean and renewable energy which has been used widely. But, designing and building of underground engineering become more difficulty in the area of geothermal resources, because geothermal resources can lead to high geo-temperature phenomenon of engineering geological problem. This problem has been encountered during construction of many underground engineering at home and abroad. Of these engineering, Bulunkou-Gonggeer hydroelectric power diversion tunnel and Qirehater hydroelectric power diversion tunnel located on Kala-Kunlun Mountain of Pamirs can be as typical engineering. During construction of Bulunkou-Gonggeer hydroelectric power diversion tunnel, the highest temperature of wall rock mass of tunnel is 97℃, and the highest temperature of steam water ejecting from joints and fissures is 140℃,the length of high geo-temperature tunnel is 4km. As for as Qirehater hydroelectric power diversion tunnel is concerned, the highest temperature of wall rock mass of tunnel is 119℃, and the highest temperature of steam water ejecting from joints and fissures is 174℃,the length of high geo-temperature tunnel is 3.5km. The length of tunnel whose temperature wall rock mass of tunnel exceeds 90℃is larger than 900m. High geo-temperature problem of the two tunnels is uncommon in the field of underground engineering. In this paper, cause of high geo-temperature of underground engineering in this area is talked about, authors consider that the main causes include activity regional structure, high regional heat flow background value, good rock conditions, poor underground water cyclic conditions, thermal conductivity rock mass or joint and small fault. Based on above discussion, authors consider that in the investigation stage of underground engineering, it is necessary to done that regional geothermal environment survey, thermal spring survey and geothermal parameters testing for those engineering which may encounter high geo-temperature during the period of designing and building. In this paper, author study high geo-temperature phenomenon which is one kind of uncommon and special geological problem during construction of underground engineering in home and abroad, activity regional structural environment and high regional heat flow background value are the essential reasons which lead to high geo-temperature phenomenon of underground engineering.