Abstract: A large amount of biogas slurry rich in nutrients such as nitrogen and phosphorus is generated as a by-product with the rapid development of large-scale biogas projects and the biogas power generation industry, which will cause secondary pollution to the environment if not effectively treated. Microalgae production featuring strong environmental adaptability, rapid growth, and high photosynthetic efficiency is one of the synergistic ways to deal with energy crises, organic wastewater purification, and carbon sequestration and emission reduction. However, relatively few studies have been conducted on the interaction between multiple factors in the process of culturing microalgae using biogas slurry. Meanwhile, the culture temperature is generally high, requiring heat preservation and warming measures, and the wastewater addition ratio is generally low. Two types of biogas slurry from the anaerobic digestion of pig dung and cow dung were used in this study and the interactive effects of biogas slurry addition ratio, light intensity, CO₂ concentration, and culture temperature on the growth and nutrient removal of Chlorella sp. (FACHB-1554) and Kirchneriella obesa (FACHB-2104) were systematically studied based on a 4-factor, 5-level quadratic orthogonal rotating center combined experimental design to optimize the process conditions. The results showed that the dry mass of FACHB-1554 and FACHB-2104 increased with the increase of the culture duration, and first increased and then decreased with the increase of the biogas slurry addition ratio. FACHB-1554 was relatively more tolerant to pig manure biogas slurry with higher NH₃-N content than FACHB-2104. The growths of two kinds of microalgae exposed to CO₂ were significantly higher than those exposed to air under the same conditions. With the increase in CO₂ concentration, the dry mass of FACHB-1554 first increased and then decreased, while the dry mass of FACHB-2104 continued to increase. For the growth of two kinds of microalgae, the effect of the biogas slurry addition ratio was stronger than that of CO₂ concentration, while the effects of the light intensity and culture temperature were relatively weak. For NH₃-N and TP removal rates, the effect of the culture temperature was stronger than that of the biogas slurry addition ratio, and the effects of the light intensity and CO₂ concentration were relatively weak. The optimal process conditions of FACHB-1554 culture in pig dung biogas slurry and FACHB-2104culture in cow dung biogas slurry are as follows: biogas slurry addition ratios of 20% and 10%, light intensity of 7 000 lx, CO₂ concentrations of 10% and 12.50%, and culture temperatures of 22 ℃ and 24 ℃. Under the optimal conditions, the maximum dry mass of FACHB-1554 and FACHB-2104 reached 0.832 g/L and 0.648 g/L. Meanwhile, the removal rates of NH₃-N were 86.71% and 77.14% and the removal rates of TP were 89.31% and 78.23%, respectively. The dry mass of FACHB-1554 were 0.685 g/L and 0.796 g/L, respectively, under the pig dung biogas slurry addition ratio of 30% and the culture temperature of 18 ℃, and their nutrient removal rates were 80.97% and 78.13% for NH₃-N and 82.11% and 82.34% for TP, respectively. In comparison, the dry mass of FACHB-2104 were 0.338 g/L and 0.613 g/L, respectively, under the cow dung biogas slurry addition ratio of 25% and the culture temperature of 18 ℃, and the nutrient removal rates were 70.92% and 67.72% for NH₃-N and 71.65% and 71.92% for TP, respectively. Therefore, it was feasible to increase the addition ratio of biogas slurry and decrease the culture temperature, which provided the basic theoretical basis for further research on microalgae culture using biogas slurry and promoted the high-value utilization of biogas slurry and the low-cost development of microalgae industry.