Abstract: The fossil fish described here was collected from the Yan' an Formation (Middle Jurassic) of Ningxia, and is referred to a new species, P. ningxiaensis, of the Genus Palaeoniscinotus. It resembles Palaeoniscinotus czekanowskii in many respects, but is characterized by its fewer fin—rays of the dorsal and anal fins, oblique enamelled striae on the scales, and fewer scales of the lateral line etc. Previously Palaeoniscinotus was known only from Siberia, Russia, this new discovery is of great significance to the study of the biostratigraphy in Liupanshan Basin.