Abstract: Some Tinosaurus fossils were collected from the Quaternary caves of Luonan County，Shaanxi Province, which are well-preserved row of teeth and dentary. The dentary is stronger and has the vertical grooves between teeth on external side of ramus caused by wear of opposing upper teeth. The teeth are reducing in size from back to front. It is the first report of Tinosaurus in the Quintenary and made the record of this genus extended from early Tertiary to the Quaternary The specimens from the area show the characters of Tinosaurus well, and compared with other species of the genera they show some differences. So we record it as a new species: T. luonanensis sp. nov.