Line S2 of Beijing Suburban Railway (BCR) is a commuter rail line in Beijing. The main line runs from Huangtudian railway station in Changping District to Yanqing railway station in Yanqing District, following the old Beijing–Baotou railway, and provides faster, more frequent and convenient service than preexisting trains. The line is 108.3 kilometres (67.3 mi) in length. The train locomotives are marked "Great Wall".

BCR also known as Beijing Suburban Railway is a commuter rail service that connects urban Beijing with outlying districts beyond the reach of the city's Beijing Subway network. The suburban rail services run on existing China Railway lines.