Abstract: With survey on lithology, paleontology and contact relationship of the Taiyuan Formation in three stratigraphic areas, namely Taizihe, Dalian and Western Liaoning, the author thinks that the geological ages of lithostratigraphic Taiyuan Formation vary from place to place in Liaoning Province. The age of Taiyuan Formation in Taizihe area is the Late Carboniferous, without diachronism; whereas that in Dalian and Western Liaoning, is the Late Carboniferous-Early Permian, with apparent diachroneity.