Abstract: A new nearly complete specimen of Diandongosaurus acutidentatusShang et al., 2011 is described from the Upper Member of the Guanling Formation (Anisian, Middle Triassic) of Luoping, Yunnan Province. With the new information derived from the new specimen, some elements of the skeleton that were either uncertain or controversial in the previous studies areconfirmed and discussed, and the diagnosis of D. acutidentatus is revised. The result of our phylogenetic analysis suggests that Diandongosaurus is an eosauropterygian, closely related to the Eusauropterygia.