The aim of this study is investigate the effect of column diameter (D), height/diameter (H/D) ratio, and gas flow rate on microalgae cultivation, Haematococcus pluvialis. Bubble column reactors with various D and H/D ratio were tested to assess the hydrodynamic properties and biomass production performance. Then, H. pluvialis was cultured under outdoor autotrophic conditions using industrial flue gas. By optimizing the reactor module, reactor volume increased to 354% with minimized biomass loss. Compared to the control, developed module showed biomass and astaxanthin productivity of 0.052 versus 0.053 g/L/day, and 1.48 versus 1.47 mg/L/day, respectively. Consequently, biomass productivity was maintained with increased reactor scale, and the result is applicable to the scale up of overall microalgae cultivation process.