Abstract: In order to improve the biomass yield of Chlorella vulgaris, optimization of BG11 medium was carried out by response surface analysis. The optimal carbon and nitrogen sources for C. vulgaris were glucose and urea, respectively. An appropriate amount of seaweed liquid fertilizer could significantly promote the growth of C. vulgaris. Three most important substrates for C. vulgaris were screened via Plackett-Burman experiments using Minitab software. Optimal concentrations of the three substrates were confirmed by Box-Behnken design and response surface analysis. The results were 58mg/L of dipotassium hydrogen phosphate, 162mg/L of magnesium sulfate and 198μL/L of seaweed liquid fertilizer. Cultivated with the optimized medium, dry cell weight of C. vulgaris after 48h reached 10.09g/L, increased by 61.2% compared with the original medium. The lipids yield was 3.62g/L, and the protein yield was 3.81g/L.