Nowadays, the world is to develop renewable energy and algal biofuel is a promising alternative to fossil fuel. However the high cost of commercial culture median, like Modified Bold 3N is an insuperable bottleneck in the large-scale production of algae-based biofuels. In this paper, we use orthogonal array composite designs
(OACDs) to search optimal chemical combination settings. We initially use a 52-run OACD with six different chemicals. Data analysis suggests that two chemicals could be excluded from combination since they lack of significance. To further study, a follow-up 28-run OACD using four chemicals indicates the optimal combination settings for these chemicals.