ABSTRACT: The Early Cretaceous ostracod fauna in western Liaoning is divided into eight successive ostracod assemblages. These assemblages have provided information about age constraint of relevant nonmarine Early Cretaceous strata: Yixian Formation – Hauterivian to Barremian, probably up to Aptian; Jiufotang Formation – Barremian to Aptian; Fuxin Formation – Aptian; Sunjiawan Formation – Albian. According to the revised age for the upper part of the Yixian Formation in the Kazuo – Chaoyang Basin, which is Hauterivian – Barremian, Ziziphocypris linchengensis is the earliest record of the genus Ziziphocypris. This work demonstrates that the supra-regionally distributed ostracod species, including species of Cypridea, are useful for biostratigraphic correlation and age determination of lacustrine deposits. In contrast, the endemic Cypridea species are helpful for regional biostratigraphic correlation of scattered basins within western Liaoning.