Nishan Tunnel, located in Hanyuan County, Ya 'an City, Sichuan Province, is an important tunnel on the Dadu River of Cheng Kun Highway. The construction of this tunnel began in 1960s+0950s, and it was finally completed and opened to traffic in 1963 after 13 years of efforts.

In the process of construction, faced with complicated geological conditions and extremely high construction difficulty, the builders overcame various difficulties and adopted advanced technical means and construction methods. At that time, the construction of Nishan Tunnel was a great feat in the history of highway construction in China, which accumulated valuable experience for highway construction in western mountainous areas of China.

Nowadays, Nishan Tunnel has become an important channel connecting Sichuan and Yunnan provinces, which is of great significance to promoting regional economic development and improving local traffic conditions. At the same time, it is also an important milestone in the history of highway construction in China, representing the continuous progress and development of highway construction technology in China.