Line S2 () is a suburban rapid transit line in the Nanjing Metro system which is currently under construction. It is expected to open in 2026. The line will have passing loops for express and local services with express trains completing travel across the whole line in 30 minutes.
In 2020, the mayors of Nanjing and Ma'anshan Cities jointly signed the "Ningma Intercity Railway Co-construction Cooperation Agreement".
The tender notice for the survey, design and review of the Nanjing-Ma'anshan intercity railway was released in September 2021. The first phase of the Nanjing section will have 8 stations and 26.9 kilometers, and the second phase will have 4 stations and 11.2 kilometers.
Construction of the Ma'anshan section, an elevated line from Cihugaoxinqu to Taibai, started on 30 December 2020. The Nanjing section started construction on December 28, 2021.