In order to accumulate the basic data and the raw material for future research,paralytic shellfish poisoning(PSP)of Alexandrium catenellacultured in the laboratory was studied.Firstly,in the logarithmic phase the algae cells were inoculated,the cell growth rate kept higher in initial 8 days.After it attained the highest density of cell(2.4×10⁴ cells/mL),the algae were collected by filtration,the crude toxin was extracted by 0.05 mol/L acetic acid.Combined with the mice bioassay,the crude toxin was identified.The result showed that the major toxic component from A. catenella were C1/2,GTX4,GTX5 and NEO by high performance liquid chromatography(HPLC)and the concentrations of them were about 0.045 50,0.252 6,0.339 2,0.827 5,0.126 6 μmol/L respectively.The crude toxin was purified via SephadexG15 column chromatography and detected by fluorescence spectroscopy and the mice bioassay,and the result showed that the impurities can be effectively excluded by Sephadex-G15 column chromatography.