An incomplete postcranial skeleton of ankylosaurs from the Late Cretaceous Wulansuhai Formation at Bayan Tal of Alaten Obo, Alxa Right Banner, western Inner Mongolia is described. Its synsacrum is composed of 4 dorsosacrals and 4 sacrals, and its last paired dorsosacral rib possesses the remarkably widened and posteriorly bent distal portion. Its caudal series include two parts: 10 free caudals, and the following handle caudals that bearing the elongated neural spines, prezygapophyses and haemal spines. This ankylosaur specimen should be assigned to indeterminate species of the genus Pinacosaurus under Subfamily Ankylosaurinae. The new material indicates that Bayan Tal of Alxa Right Banner represents the third locality yielding Pinacosaurus in Inner Mongolia Autonomous Region, after Bayan Mandahu in Urad Rear Banner and “Shanlanhuduke” in Alxa Left Banner. This finding further extends the geographical distribution of Pinacosaurus, and provides more paleontological evidences for our understanding the similarity of the Late Cretaceous dinosaur faunas between Bayan Tal of Alxa Right Banner and Bayan Mandahu of Urad Rear Banner in western Inner Mongolia.