This study identifies one diatom species as Neidium beatyi after examining the specimens collected from East Dongting Lake National Nature Reserve by using light and scanning electric microscopy. The observation results demonstrate that N. beatyi possesses the following diagnostic features: (1) linearelliptic to lanceolate valve outline; (2) 3-5 longitudinal lines along two valve margins; (3) Two proximal raphe ends deflected in opposite directions, distal raphe ends forming forked two fissures and triangular apical flap present at each apex; (4) Striae 16-18/10 μm and areolae 14-18/10 μm; (5) 4-7 renilimbi surrounded each internal opening of some areolae. The study results are consistent with the morphological characteristics and quantitative characters of the type population of N. beatyi, hence it is confirmed to be N. beatyi; and add a new geographical distribution region of N. beatyi — Dongting Lake, China.