Line 3 of the Guangzhou Metro is a 65.43-kilometer (40.66 mi) rapid transit line connects Panyu Square to Tianhe Coach Terminal. The entire line, including all track and stations, is located in tunnels. Its 57.93 km (36.00 mi) main branch, excluding the 7.5 km (4.66 mi) branch between Tianhe Coach Terminal and Tiyu Xilu, is now the third longest continuous subway tunnel in the world, and the longest rail tunnel of any kind.

Tianhe District is one of the eleven districts of Guangzhou, the capital of Guangdong province. In Chinese, the name Tianhe literally means "a river in the sky/heavens", which is also a Chinese name for the Milky Way. It is bordered by Yuexiu District on the west, Baiyun District on the north and Huangpu District on the east. Haizhu District is on its south, though they are separated by the Pearl River.