Abstract: Abstract: This study mainly focused on the following problems like the higher cost of adding nitrogen and phosphorus in chlorella culture; the delayed and ineffective use of biogas slurry containing rich nutrient elements just as nitrogen, phosphorus, and so on after anaerobic fermentation; the easily contaminated microalgae caused by undesired microbes in microalgae culture; the higher cost of microalgae culture due to the biogas slurry pretreatments like sterilization and so forth when biogas slurry was serving as the culture medium; etc. The culture medium was the mixture of BG11 medium and biogas slurry from straw by anaerobic fermentation for 30 days. The biogas slurry fermented from straw was non-sterilized and relatively simple in composition. The algae species FACHB-5 and FACHB-8 chlorella were used. An artificial climate incubator was also used, in which the temperature for microalgae culture was kept at (26±1)℃, the light intensity was 4 000 lx, the light time was 24 hours continuously, and the ventilation volume was 1.5 L/min. In the experiment, the total nitrogen at the beginning was 180, 215 and 297 mg/L respectively in the experimental medium groups. The addition content of biogas slurry was 20%, 30% and 40% separately; and the results showed that the total nitrogen content of culture liquid was reduced to 6, 8 and 12 mg/L with the different biogas slurry treatments (20%, 30% and 40%), respectively, and the removal rate of total nitrogen was more than 96%. The total phosphorus content at the beginning was 14, 19 and 24 mg/L respectively in the experimental medium groups with the addition of biogas slurry was 20%, 30% and 40%, separately; At the end of the experiment, they reduced to less than 2 mg/L, and the removal rate of total phosphorus was more than 92%. Chemical oxygen demand (COD) content at the beginning was 4 500, 6 993 and 9 366 mg/L respectively, in the experimental medium groups with the addition of biogas slurry was 20%, 30% and 40%, and at the end of the experiment they reduced to 160, 400 and 540 mg/L respectively, the removal rate of COD was more than 90%. The experimental results showed that both FACHB-5 and FACHB-8 algae species could well adapt to biogas slurry which was relatively high in COD content from straw by anaerobic fermentation, and could well make the use of and remove the organic pollutants from biogas slurry. Compared with FACHB-5 algae species, FACHB-8 algae species needed shorter time to adapt, and had stronger adaptability to biogas slurry. What's more, there was a strong correlation between the degradation of organic pollutants and the growth of chlorella in every experimental medium group. The study may lay a theoretical foundation for the application of biogas slurry which will be directly used in microalgae culture, and may have the magnificent significance for large-scale microalgae culture.