ObjectivernWest Liaoning has a large area of Mesozoic continental strata, which is unique for the study of Mesozoic continental strata in China and even all over the world. The Jurassic-Cretaceous boundary of Mesozoic continental strata in West Liaoning has been controversial since 2013 when the Jurassic-Cretaceous boundary at 145 Ma was established in the intational stratigraphic table. The Tuchengzi Formation is a key Mesozoic stratum in West Liaoning, which is widely distributed and has a clear top and bottom. The determination of the age of the Tuchengzi Formation can provide important constraints on the Jurassic-Cretaceous boundary in West Liaoning and even east China, as well as on the study of other major geological problems in east China. However, because of the domination of coarse clastic rocks and few fossils, paleontologists have been debating the age of the Tuchengzi Formation. At the same time, the geochronogical study is very difficult due to the lack of volcanic rocks in the Tuchengzi Formation. Rock assemblages can divide the Tuchengzi Formation into three sections from bottom to top. So far, several ages have been obtained from the first and second sections of the Tuchengzi Formation, but not yet in the third section. In this paper, three new ages have been reported for the first time for tuff interbeds within the third section of the Tuchengzi Formation. Combined with the analysis of sedimentary facies, the Jurassic-Cretaceous boundary of continental strata in West Liaoning has been determined.