Abstract: Fossil cricetids found from the Bahe Formation, Lantian are assigned to Nannocricetus primitivus sp. nov. and Kowalskia indet. respectively by their dental characters and measurements. The new species Nannocricetus primitivus is characterized by its smaller size and having single cusped anteroconid of m1 on moderate and heavily worn teeth, presence of metalophulid I, absence of metalophulid II, no mesoloph on upper molars, absent or very weak mesolophid on lower molars, and very reduced M3. Magnetostratigraphic results of the Bahe Formation indicate that the localities produced Nannocricetus primitivus range from the early Late Miocene to the middle Late Miocene (~10.2−8 Ma). The primitiveness of the new species and its earlier geologic records suggest that it might be the direct ancestor of Nannocricetus mongolicus. The turnover from Nannocricetus primitivus to N. mongolicus should occur at about 7~8 Ma. There found only one m2 of Kowalskia. The fossil level of Kowalskia indet. is in the upper part of the main section, dated to slightly earlier than 8 Ma. Except the material from Lufeng (MN11), the Lantian material is one of the earliest emigrants from the western Eurasia.