['To investigate the inhibitory effects of single and compound phenolic acids on mixed algae.', 'Salicylic acid, cinnamic acid and pyrogallic acid were chosen individually or in pairs to act on mixed algae of Microcystis aeruginosa and Chlorella pyrenoidosa.', 'Three phenolic acids that singled or paired showed certain inhibitory effects on the mixed algae, of which were pyrogallic acid > salicylic acid > cinnamic acid in single phenolic acid, the EC50s of the three phenolic acids on the mixture of Microcystis aeruginosa and Chlorella pyrenoidosa were 7.87, 64.90 and 89.34 mg/L at the day 6; and inhibition of the paired phenolic acid group was pyrogallic acid & salicylic acid group > pyrogallic acid & cinnamic acid group > salicylic acid & cinnamic acid, the first 2 groups had synergistic algal inhibitory effects and the last paired group showed additive action.'] Does [ Joint inhibitory effects research on Microcystis aeruginosa and Chlorella pyrenoidosa of phenolic acids ]?