Phytohormones are widely known to regulate plant growth under environmental stress, however, their roles of microalgae are not clear during the antibiotic wastewater treatment. A hypothesis was proposed that phytohormones were capable to relieve the inhibition of microalgae growth and improve the bioresources recovery from antibiotic wastewater. Chlorella and enrofloxacin (ENR) were utilized to simulate the antibiotic wastewater treatment by microalgae, and explored the roles of p-hydroxybenzoic acid (pH BA). With 10 mg/L ENR and 1 μM pH BA condition, the Chlorella biomass increased by 23%. Moreover, lipid production increased by 30%. Trace amounts of pH BA improved microalgae growth and lipid accumulation by up-regulating photosynthesis, glycolysis, and TCA cycle. Furthermore, pH BA stimulated the signal transduction pathways of microalgae to improve antioxidant defense capability. Therefore, pH BA enhanced tolerance of ENR and improved microalgae lipid production. This study provided a new clue into using microalgae to recover high-value bioresources from antibiotic wastewater. All rights reserved, Elsevier.