Abstract: This paper reports a diatom assemblage found by the author from the Upper Tertiary continental strata in Shangdu County in Niemongol Autonomous Region and Dunhua County in Jilin Province of China. The diatom assemblage in Shangdu County comprises 4 new species and 2 new varieties: Tetracyclus ellipticus var. ovalifolium Li; Tetracyclus ellipticus var. rostrata Li; Tetracyclus jaoi Li; Tetracyclus navicularis Li; Tetracyclus shangduensis Li and Tetracyclus sinensis Li. From the Miocene of Dunhua County; JilinProvince are recorded 2 new species: Tetracyclus dunhuanensis Li and Tetracyclus ovaliformis Li.

Key words: Tetracyclus, T.dunhuanensis, T.ellipticus var.ovalifolius, T.ellipticus var. rostrata, T.jaoi, T.navicularis, T.ovaliformis, T.sinensis, T.shandunensis