Abstract: Prorocentrum donghaiense was cultured with PM4A multi-phosphorus plate (a total of 59 phosphorus sources) to study the effect of different phosphorus forms on its proliferation.Results showed that the 47 kinds of phosphorus sources (including 42 organophosphorus and 5 inorganic phosphorus) could be utilized by Prorocentrum donghaiense. Prorocentrum donghaiense had higher uptake efficiency for organic phosphorus than that for inorganic phosphorus,mainly for organic phosphorus containing C-O-P ester bonds,including phospho-glycolic acid,D-mannose-1-phosphate and phosphoenol pyruvate.These indicated that organic phosphorus might be an important phosphorus source affecting the growth of algae,providing a scientific basis for the outbreak and solutions of Prorocentrum donghaiense red tide,which was of practical significance.