Line 6 of the Beijing Subway is a rapid transit line in Beijing. The line runs from Jin'anqiao in Shijingshan District to Lucheng in Tongzhou District. It serves important residential areas such as Changying, Chaoqing, and Dingfuzhuang, in addition to important commercial and business areas such as Financial Street, Beijing CBD and the sub-administrative center in Tongzhou District. Like Line 7, Line 6 provides relief to the parallel Line 1, which is the second most used subway line in Beijing, after Line 10. Line 6 is the second longest subway line in Beijing. A complete journey from end to end takes about an hour and 25 minutes on a local train and express trains reducing end to end travel time by 7 minutes.

The Beijing Subway is the rapid transit system of Beijing Municipality that consists of 27 lines including 22 rapid transit lines, two airport rail links, one maglev line and 2 light rail lines, and 490 stations. The rail network extends 836 km (519 mi) across 12 urban and suburban districts of Beijing and into one district of Langfang in neighboring Hebei province. With 3.8484 billion trips delivered in 2018, an average of 10.544 million trips per day, the Beijing Subway is the world's busiest metro system. Single-day ridership set a record of 13.7538 million on July 12, 2019. Being 836 kilometres (519 mi) in system length, the Beijing Subway is the longest metro system by route length, surpassing the Shanghai Metro in December 2023.