swine wastewater,Chlorellaand inoculated sludge were used to construct an algae-bacteria symbioticsystem. The effects of different algae-bacteria ratios (1 ∶ 0,1 ∶ 0.2,1 ∶ 0.5,1 ∶ 1,1 ∶ 5) on the growthof microalgae and the component accumulation in microalgae,as well as nitrogen and phosphorus trans⁃formation mechanisms were explored. The results showed that with an algae-bacteria ratio of 1 ∶ 0.2,the microalgae component was dominated by lipids in pure algae-cultivation system,and the concentra⁃tion and protein content of microalgae in the algae-bacteria symbiotic system were 800 mg·L-1and56.8%. Due to the synergistic effect of algae and bacteria,the proportion of the nitrogen and phosphorusremoved by biological assimilation increased. The main pathways of nitrogen removal were biological as⁃similation (38%) and nitrification and denitrification (62%). The chemical precipitation (82%) andbiological assimilation (18%) were the main pathways of phosphorus conversion. When the algae-bac⁃teria ratio was 1 ∶ 0.2,the removal efficiencies of TP,TN and NH+4-N were the best,which were 76.0%,32.7% and 31.7%,respectively. When the algae-bacteria ratio was 1 ∶ 5,the removalefficiency of soluble organic matter was the best,reaching 87.8%.