Abundant foraminiferal fossils (Ammonia) and their associated ostracoda and charophyta fossils were discovered for the first time in Quaternary sediments of hole K1 in Lop Nur, Xinjiang. Ammonia is a common genus occurring from the Miocene to the present, which belongs to paralic species groups. Lop Nur had been far from the sea in the Quaternary; so marine transgression was not able to take place. According to the history of Cenozoic transgression in the Tarim basin, the authors propose that the origin of species of foraminifers in Quaternary sediments of hole Kl in Lop Nur was related to the relic sea.