A new Middle Jurassic xinjiangchelyid turtle from China, Xinjiangchelys chowi sp. nov., is described from the Toutunhe Formation of the southern Junggar Basin, southwest of Urumchi (NW China). The material consists of a nearly complete carapace and the right hypoplastron. It shows important autapomorphies of the family Xinjiangchelyidae and the genus Xinjiangchelys: first neural larger than second, anterior peripherals guttered, posterior peripherals expanded, a reduced first thoracic rib, and lateral pegs of the bridge of the plastron. It is distinguished from all other species of Xinjiangchelys by the following autapomorphies: a first costal rib with free rib end, at least two anterolateral peripheral fontanelles of the carapace, a thin plastron with large lateral fontanelles, and a median hypoplastral suture with strong pegs. These features indicate that X. chowi is the most derived xinjiangchelyid turtle hitherto known. Together with X. tianshanensis, this is the oldest xinjiangchelyid turtle known so far. Therefore, a long ghost lineage must be claimed for the Xinjiangchelyidae.