The Beijing Subway is a rapid transit rail network that serves the urban and suburban districts of Beijing municipality. The subway is owned by the city of Beijing and has two operators, the wholly state owned Beijing Mass Transit Railway Operation Corp., which operates 13 lines, and the Beijing MTR Corp., a public-private joint-venture with the Hong Kong MTR, which manages 2 lines.

The subway's first line opened in 1969, and the network now has 15 lines, 192 stations and 372 km (231 mi) of track in operation. It is the oldest subway in mainland China. Among the world's metro systems, the Beijing Subway ranks fourth in track length after the metros of Shanghai, London and Seoul, and fourth in annual ridership after those of Tokyo, Seoul, and Moscow.

In 2011, the Beijing Subway delivered over 2.18 billion rides, and on September 9, 2011, set a single-day record of 7.57 million. All but two of Beijing Subway's 15 lines were built within the past decade. The most recent additions, Line 9, along with sections of Lines 8, 15 and Fangshan, entered into operation on December 31, 2011. Despite the rapid expansion, the existing network cannot adequately meet the city's mass transit needs and extensive expansion plans call for 19 lines and over 703 km (437 mi) of track in operation by 2015 and 1,000 km (620 mi) by 2020. The network is set to reach 420 km (260 mi) by the end of 2012.