Guanjiao Tunnel on XiningGolmud 2nd Line of QinghaiTibet Railway is the first railway tunnel in China whose length is larger than 30 km. In this paper, studies and results are as follows: 1) The technologies, such as ventilation gallery separated by inclined shaft, mucking by belt conveyor and increasing the air supply, are used, so as to reduce the environmental pollution, improve the construction efficiency and solve oxygen supply problem. 2) The comprehensive grouting for karstic fissurewater and rational drainage arrangement are used so as to solve the continuous highpressure water inrush problem. 3) Technologies, such as structure type adjustment, primary support strengthening and deformation allowance setting, are used, so as to control the large deformation of fault. 4) The “piston air” is used, the smoke distribution laws in tunnel when fire disaster happens is studied; and the jet ventilation fan and disperse ventilation by vertical shaft are used. The results can provide guidance for construction of extremelylong tunnel of similar projects in the future.