Abstract: A co-culture system of lipid-rich Chlorella vulgaris and Aspergillus oryzae was established to investigate the effects of different initial microalgal and fungal inoculation ratios on pollutant removals and biomass change in simulated livestock wastewater. The results showed that C. vulgaris and A. oryzae had synergistic effects in wastewater treatment, and co-culture system was more beneficial to the removal of pollutants than C. vulgaris alone. The optimal inoculation ratio of C. vulgaris-A. oryzae was 25:1, and the removal efficiencies of total nitrogen (TN), ammonia nitrogen (NH₄^%2B-N), total phosphorus (TP), chemical oxygen demand (COD) and copper were 72.51%, 71.19%, 92.23%, 91.47% and 90.38%, respectively. In addition, the co-culture system also showed good biological removal for three sulfonamides. The removals of sulfadiazine (SMZ), sulfamethoxazole (SMX) and sulfamethoxine (SMM) were 57.61%, 58.31% and 50.48%, respectively, which were 34.89%, 25.43% and 45.71% higher than those of microalgae alone. Filamentous fungi were easy to form spherical particles with microalgae to realize the harvesting of microalgae. The maximum harvesting efficiency was 76.91%, and the biomass after harvesting reached 1.26 g/L. The contents of protein, polysaccharide and lipid were 111, 438 and 249 mg/g, respectively. Therefore, the co-culture of C. vulgaris and A. oryzae not only effectively removed the pollutants in livestock wastewater, but also realized the resource utilization of biomass, which exhibits potential application in livestock wastewater treatment.