On the map of China, drawing a straight line from Heihe in Heilongjiang to Tengchong in Yunnan marks the famous "Hu Huanyong Line." At both ends of this dividing line, the distribution of energy is high in the west and low in the east, with a huge gap. Over 80% of energy resources are distributed in the western and northern regions, while over 70% of energy consumption is concentrated in the eastern and central regions. Effectively utilizing and leveraging the advantages of western energy resources over long distances is key to determining the success or failure of China's clean and low-carbon energy transition.

　　To change the unbalanced energy layout, in 2000, the country officially proposed the implementation of the West-to-East Power Transmission strategy. As a landmark and backbone project of the "Western Development" strategy, the West-to-East Power Transmission was fully launched. In 2004, the Guizhou-Guangdong DC transmission project was put into operation, and new achievements were made in the construction of the southern corridor, achieving the goal of transmitting 10 million kilowatts of electricity to Guangdong a year ahead of schedule. Since 2003, the Three Gorges Hydropower Project in the central corridor has begun transmitting electricity to East China through the ±500 kV Longzheng DC line. Starting in 2006, the Shenmu and Fugu thermal power plants in Shaanxi began transmitting electricity to North China, and the sending end of the northern corridor began to expand towards the northwest energy base.

　　In the second decade of implementing the West-to-East Power Transmission strategy, the scale of the project, marked by ultra-high voltage transmission, has increased exponentially, fully supporting the construction of western energy bases and meeting the electricity demand in the eastern and central regions. With the operation of the 1000 kV ultra-high voltage AC demonstration project from Southeast Shanxi to Nanyang to Jingmen in 2009, and the ±800 kV ultra-high voltage DC transmission project from Xiangjiaba to Shanghai in 2010, the range and level of optimized allocation of energy resources in China have significantly improved.

　　In 2014, to implement the "Air Pollution Prevention and Control Action Plan," the National Energy Administration proposed to accelerate the construction of 12 key transmission corridors for air pollution prevention and control. The West-to-East Power Transmission, primarily based on ultra-high voltage transmission, began to carry a new historical mission, effectively promoting air pollution prevention and control. By 2018, all 12 key transmission corridors for air pollution prevention and control were completed, adding 80 million kilowatts of cross-regional transmission capacity in the eastern and central regions, equivalent to reducing coal consumption by 180 million tons annually in these areas. In 2018, to further promote energy transition and expand effective investment, the state increased efforts to address infrastructure shortcomings, and the "Five AC and Five DC" ultra-high voltage projects proposed by the State Grid were included in the national power planning. In 2021, the National Energy Administration proposed to plan and construct 12 ultra-high voltage corridors during the "14th Five-Year Plan" period to support comprehensive energy bases, achieving the delivery of clean energy from the west to the eastern load centers.

　　Today, the West-to-East Power Transmission project has formed three major corridors: the northern, central, and southern corridors. The northern corridor mainly transmits electricity from provinces such as Xinjiang, Inner Mongolia, Shaanxi, and Ningxia to North China and East China. The central corridor mainly transmits electricity from provinces and cities such as Sichuan, Chongqing, and Hubei to Central and East China. The southern corridor mainly transmits electricity from provinces such as Yunnan, Guizhou, and Guangxi to South China.

　　By the end of 2022, 72 West-to-East Power Transmission projects had been completed nationwide, with a transmission capacity reaching 320 million kilowatts. The northern, central, and southern corridors reached 90 million, 170 million, and 60 million kilowatts, respectively; the State Grid's West-to-East Power Transmission capacity reached 260 million kilowatts, with a total of 33 ultra-high voltage projects completed.