Qinghai-Tibet railway is the first railway line with the highest altitude in China, even in the world. It is the key project in the National Tenth Five-year Plan. The construction is under severe geological environment, rarefield air. The highest altitude is above 5500m, and the average altitude is around 4000m. It is with many difficulties in construction and operation. With close cooperation and joint efforts of the builders, all 44 substations have been successfully put into service, which gave a solid support for the safety performance of the line.