Line 4 of Chongqing Rail Transit is a rapid transit line in Chongqing, China.

[4] In June 2018, debugging of the first segment of Phase I commenced.

[6] Phase 1 of Line 4 began operating on December 28, 2018.

Phase 2 (Tangjiatuo – Huangling) is 32.8 km (20.4 mi) in length (21.25 km (13.20 mi) underground and 11.55 km (7.18 mi) elevated[7]) with 15 stations (10 underground stations and 5 elevated stations).

[10] The Western extension of Line 4 started construction in March 2021.