[6] Line 3 will initially use 4-car Type A rolling stock but platforms are designed to support expansion to 8-car trains.

In the late 1990s, one draft of the subway plan showed Line 3 running from Xiaomeichang to Cuigezhuang.

[13] On March 15, 2012, Line 3 was reportedly planned to run from Tiancun station to the eastern suburbs of Beijing in Gaoxinzhuang and Pingfang and to be built by 2020.

[15] In January 2013, subway planners were examining whether to extend the Line 3 through the city centre given the concentration of historic relics in the area.

[23] On May 1, 2024, the Beijing Municipal Commission of Planning and Natural Resources adopted station names of line 3 phase 1.

[25] On September 29, 2024, Beijing Infrastructure Investment (BII) company announced the planning scheme of line 3 eastern extension, a 6.4 km underground section with 5 new stations, but of which the potential termini Caogezhuangbei will only have reservation places for future plans.