Line 4 (Beijing Subway)

Line 4 of the Beijing Subway (Chinese: 北京地铁4号线; pinyin: běijīng dìtiě sìhào xiàn) is a subway line in Beijing's mass transit network. It entered into operation on 28 September 2009, and runs from north to south, parallel and to the west of Line 5, through Haidian, Xicheng, and Fengtai Districts in the western half of the city. It runs from Anheqiao North in the north and ends at Gongyixiqiao in the south, but the 4-Daxing connected line runs all the way to Tiangongyuan in Daxing. All stations are underground except Anheqiao North. It is 28.2 km (17.5 mi) long with 24 stations. Riding on this line starts from a fare of RMB(¥) 3.00 depending on the distance traveled. Line 4's color is teal.

Line 4 and Daxing line operate as a single line although they are classified as separate lines. Two different services are run during the day: A full service covering both Line 4 and Daxing line and a shorter service that ends at Xin'gong station, the first station of Daxing line. Combined, the Line 4/Daxing Corridor carries an average of 1.24 million passengers every day in 2017, growing to about 1.4 million passengers per day by 2019.