This study was conducted to investigate the effect of influent concentrations in SBR process using activated algae. Modified McKinney equation was applied to this study for understanding of results. Influent concentrations affect the active biomass(MaA, MaB) and Algae/Bacteria ratio. The initial Algae/Bacteria ratio of 1.0 were changed to 2.78, 2.18, 1.29 and 0.97 at Case 1(300/50/10), Case 2(300/100/10), Case 3(600/50/10), Case 4(600/100/10), respectively. COD removal efficiency were obtained above 93%, T-N removal efficiency were 49.85% and T-P removal efficiency were 12~67% without aeration, respectively. The results showed that modified McKinney equation application was useful for interpreting the activated algae processes. The results of modified McKinney equation indicated that the fraction of nitrogen removed by denitrification or stripping was increased to the extend of 75.1% with increasing CODcr. And the fraction of phosphorus removal by precipitation was increased to the extend of 77.4% with increasing CODcr.