Guangyang District in the context of Langfang

The Beijing Subway is the rapid transit system of Beijing Municipality that consists of 29 lines including 24 rapid transit lines, two airport rail links, one maglev line and two light rail tram lines, and 524 stations. The rail network extends 879 km (546 mi) across 12 urban and suburban districts of Beijing and into one district of Langfang in neighboring Hebei province. In December 2023, Beijing Subway became the world's longest metro system by route length, surpassing the Shanghai Metro. With 3.8484 billion trips delivered in 2018 (10.544 million trips per day) and single-day ridership record of 13.7538 million set on July 12, 2019, the Beijing Subway was the world's busiest metro system in the years immediately prior to the outbreak of the COVID-19 pandemic.

The Beijing Subway opened in 1971 and is the oldest metro system in China and on the mainland of East Asia. Before the system began its rapid expansion in 2002, the subway had only two lines. The existing network still cannot adequately meet the city's mass transit needs. Beijing Subway's extensive expansion plans call for 998.5 km (620.4 mi) of lines serving a projected 18.5 million trips every day when Phase 2 Construction Plan finished (around 2025). The most recent expansion came into effect on December 15, 2024, with the openings of Line 3 and Line 12 and an extension of the Changping line.