Tongmi line of Beijing Suburban Railway (BCR) (Chinese: 北京市郊铁路通密线; pinyin: Běijīng Shìjiāo Tiělù Tōngmì Xiàn), formerly known as Jingcheng line, is a commuter rail line in Beijing. It opened on 30 June 2020.^[1]

The main line runs on the existing Beijing–Chengde Railway, and the branch line runs on the existing Beijing–Tongliao Railway. It runs from Tongzhou West to Miyun North (main line) or Huairou North (branch line). The line is 84.2 km (52.3 mi) in length.^[2]