Abstract: Compsopogon specimens were collected in Dingnanshui River from Longchuan County,Guangdong Province in August 2009.The morphological characters of the specimen were similar to Compsopogon caeruleus and C.sparsus.Plants were 10-18 cm high and 180-270 μm in diameter,main axes were slight constricted.Axial cells were nearly spherical and spheroidic,100-110 μm high and 150-200 μm in diameter.Cross wall was constricted apparently.Cortical cells were one layered while 2-3 layered at constricted axial cells,polygonal or ovoid shaped,25-35 μm long,20-25 μm in diameter.Branching horizontal and lateral,some basal cells specialized as rhizoid on the plants.Apex of branches acuminate,acute or binary.Monosporangia spherical,10-14 μm in diameter.The specimen may be a transitive type of C.caeruleus and C.sparsus in evolution.