Abstract: Through setting different light-dark cycle,function parameters of M.aeruginosa,such as growth curve and total phosphorus(TP),were measured to explore effects of duration of light irradiation on growth and phosphorus metabolism of M.aeruginosa in the presence of adnascent Pseudomonas sp..Results show that the specific growth rate of M.aeruginosa increased with the duration and the logarithmic growth of M.aeruginosa promoted release of P from Pseudomonas sp..The promoting effect of M.aeruginosa was influenced by its phosphorus uptake ability which was determined by its P-consuming growth and concentration of P.The P content of M.aeruginosa decreased during the experiment period,which was caused by the increasing biomass and P consumption,instead of the uptake of phosphorus.