The effects of culture conditions on the growth of Chlorella. sp were studied. The nutrient factors showed obvious effect on Chlorella.sp. The culture conditions based on BG-11 were optimized by orthogonal experiments: Na2CO 3 0.02g/L, the initial pH 6, the ratio of nitrogen to phosphorus 30, inoculum 5%, temperature 25℃, illumination 8800lx. Under the optimal culture conditions, the growth rate of Chlorella.sp was enhanced significantly.