Abstract: The genus Pinnularia Ehrenberg is one of the largest diatom genera in the world. Pinnularia is closely related to Caloneis Cleve (1891), suggesting that they should be considered as the same genus. Now, the two genera are listed as two single genus in the taxonomy system of Hustedt. During the investigation of diatoms from Xingkai Lake, we observed 45 taxa in Pinnularia that preferred to live at pH 6 to 7. Six of 45 taxa were reported as newly recorded species in China that includes Pinnularia aestuariiCleve, Pinnularia cruxarea Krammer, Pinnularia distinguenda var. obtuse Krammer, Pinnularia gibbiformis Krammer, Pinnularia notabilisKrammer, and Pinnularia perspicua Krammer. The morphological characteristics and the morphological differences with other similar species were described in detail. This investigation provides the basic information of algae in Xingkai Lake.