Line 3 of the Guangzhou Metro (Chinese: 广州地铁3号线; pinyin: Guǎngzhōu Dìtiě Sān Hào Xiàn) or Southern-Northern Express Line (Chinese: 南北快线; pinyin: Nán Běi Kuài Xiàn) is a 67.3-kilometer (41.8 mi) line connecting Tianhe Coach Terminal to Panyu Square. The entire line, including all track and stations, is underground, making it the longest fully underground rapid transit line in the system. Furthermore, the 60.4 km (37.5 mi) main branch is the longest rail tunnel in the world, and one of the ten longest tunnels of any kind. The Y-shape is created by a 6.9 km (4.3 mi) branch between Tianhe Coach Terminal and Tiyu Xilu,
Line 3 is split into two sections Shiqiao Line (southern section) (Chinese: 市桥线; pinyin: Shìqiáo Xiàn) and Airport Line (northern section) (Chinese: 机场线; pinyin: Jīchǎng Xiàn) and are branded with the same color: orange.
Line 3 was built in four main stages, opened over a five-year period:
- December 26, 2005: Guangzhou East Railway Station – Kecun
- December 30, 2006: Kecun – Panyu Square
- December 30, 2006: Tianhe Coach Terminal – Tiyu Xilu
- October 30, 2010: Guangzhou East Railway Station – Airport South