Six new species of the diatom genus Gomphonema Ehrenberg are described from lakes, swamps, bogs and streams from the Great Xing'an Mountains region of Northeastern China. Descriptions are based on light and scanning electron microscope observations of valve shape, size and ultrastructure. Of the six new species, four are known from the Great Xing'an Mountains only, while two others have been recognized in nearby Mongolia. All six species are known from habitats that are circumneutral to alkaline. Each species is described and compared with similar taxa. These new species descriptions, in addition to the recognition of other new species in the region, suggest aquatic habitats in the Great Xing'an Mountains may support an endemic diatom flora.