D-series trains () trains are a type of train service offered by China Railway. They are further divided into two types: One type is an electric multiple unit EMU train that runs on high-speed or rapid railways (and in the early days, also on upgraded conventional railways). These trains are numbered D9XX (sleeper trains) and D plus four digits, with a maximum operating speed of and make more stops than G-series trains. The other type runs on classic rails and is operated by CR200J EMUs as a replacement for traditional trains. These have a maximum operating speed of , the same as Z-series trains, and are numbered D1 to D899.
The D-series trains often use EMUs with a designed speed of or , covering both Hexie (CRH series) and the Fuxing (CR series).