The growth condition of Chlorella spp was optimized to increase its biomass. Under the aseptic culture condition, major nutritional factors for Chlorella spp growth, such as Na2CO3, NaNO3, KH2PO4 and MgSO4 were optimized. Trace elements and pH value had a prominent influence on the growth of Chlorella. Optimized culture medium program was as follows: Na2CO3 0.02g/L, NaNO3 2.0g/L, KH2PO4 0.02g/L, MgSO4 0.1g/L and ambient conditions of pH value 6.0. The research could lay foundation for t the cultivation of Chlorella spp. on a large scale.