Abstract: The effects of Ni on the growth,absorption spectrum of intact cells and phycobiliprotein and content of phycobiliprotein of Microcystis aeruginosa was studied,in order to explore the influence of microelement on algal blooms.The results indicated that:(1) the growth of the algal cells was promoted under the low concentrations (0.10μg/mL) of Ni but inhibited under the high concentrations (0.30-1.00μg/mL);(2) the absorption spectrum of intact cells moved and receded,it showed that the characters of chlorophyll and phycobiliprotein were changed and the light-harvesting capability of the cells was inhibited;(3) the low concentrations (0.30μg/mL) of Ni made higher peak of absorption spectrum of the phycobiliprotein,while the high concentrations (0.401-1.00μg/mL) made it lower;(4) the content of phycocyanin (PC) was increased under the low concentrations (0.30μg/mL) of Ni and reduced under the high concentrations (0.40-1.00μg/mL),while the content of allophycocyanin (APC) was reduced under any concentration of Ni treatment.