The present study aimed to optimize the process parameters for the surfactant sodium dodecyl sulfonate (SDS)-ultrasonic extraction technology of polyphenols from Atractylodes macrocephala Koidz grown in Qimen (Qi Baizhu). The effects of polyphenols from Qi Baizhu (QBP) on antioxidant and antibacterial activities were explored. The results showed that the optimal process conditions were as follows: SDS concentration 0.47%, extraction temperature 48 ℃, ultrasonic power 150 W, ethanol concentration 64%, extraction time 15 min, and solid-liquid ratio 125 （g/mL）. Under these conditions, the content of QBP was (38.53±0.51) mg/g. QBP exhibited strong DPPH and ABTS free radical scavenging capacities with IC₅₀ values of 0.056, 0.050 mg/mL, respectively. QBP also exerted the inhibition effects on four common bacterial strains. There was a good linear dependence between the antibacterial capacity and the concentration. Its minimum inhibitory concentration (MIC) against E. coli, S. aureus and P. aeruginosa was 0.25 mg/mL, while the MIC against B. subtilis was 0.50 mg/mL.