Abstract: A strain of microalga that has a strong ability in the utilization of organic compounds was isolated from Qinghe River in Beijing and identified as Chlorella sp. The effects of nitrogen compounds and carbon-to-nitrogen mass ratio on the growth of this isolated Chlorella sp were investigated in batch cultures. Using glucose as the sole carbon source, both potassium nitrate and urea could be used as the sole nitrogen sources to support the continuous growth of Chlorella sp, respectively. When ammonium chloride was used as the sole nitrogen source, the growth of Chlorella sp could be apparemly inhibited by the rapid decrease in pH of culture solution. When glucose and potassium nitrate were used as the sole carbon and nitrogen sources, respectively, the growth ofChlorella sp increased with the increase of carbon-to-nitrogen mass ratio in range from 5 to 20, and the maximum OD_680nm of 73.8 was obtained.