Abstract: Effect of scooping blue algae out of the culture solution of Microcystis aeruginosa at its logarithmic phase and stationary phase on growth of Microcystis aeruginosa was investigated through measuring cell density of Microcystis aeruginosa cultured indoors using the once-for-all culturing method.Results show that the scooping at different growth stages rendered significantly different impacts on subsequent growth of Microcystis aeruginosa.When scooping was done at the logarithmic phase,Microcystis aeruginosa could go on growing well.Intensive scooping would prolong Microcystis aeruginosa′s logarithmic growth period with the maximum population density displaying a rising trend.And when scooping was done at the stationary stage,Microcystis aeruginosa would quickly restore its stationary stage,thus inhibiting its subsequent growth,Measurement of MDA accumulation and SOD activity of the algae indicates that scooping of blue algae eliminates the density-related restraint on growth of Microcystis aeruginosa during its growing period,and delays aging of the algae.