The growth and the utilization of dissolved organic phosphorus(DOP) of Microcystis neruginosa and Chlorella pyrenoid-osa were studied under unialgal batch culture condition. Three different forms of phosphorus sources; glucose-l-phosphate, cyclic 3'S'-adenosine monophosphate(c-AMP ) and adenosine triphosphate(ATP),were examined in our study. The results imply that although both M. aeruginsoa and C. pyrenoidosa were able to utilize those DOP, M. aeruginosa grew better than C. pyrenoidosa.Particularly, M. neruginsoa could effectively utilize glucose小phosphate, and its maximum cell abundance was as high as that un-der phosphate condition. Compared with c-AMP, glucose-I-phosphate and ATP were more efficiently uptake by algae. It demon-strafed that alkaline phosphatase was very important for the utilization of DOP. The proportion of DOP to total dissolved phosphorus was pretty high in the eutrophic lake, therefore, the efficient utilization of dissolved organic phosphors may be a competitive advan-tage for M. aeruginsosa to become dominant species in ihis water environment.