The invention discloses an application of pulsatilla saponin A3 in inhibiting the growth of multi-drug-resistant Providencia rettgeri. According to the invention, the pulsatilla saponin A3 has good in-vitro killing effect on human-derived Providencia rettgeriis with resistance to ampicillin, ampicillin/sulbactam, cefazolin, cefotetan, ceftriaxone, ceftazidime, tobramycin, piperacillin tazobactam,ciprofloxacin, levofloxacin, amikacin, compound phenoxymine, cefepime, ertapenem, imipenem, aztreonam and gentamicin, can inhibit in-vitro growth of the multi-drug-resistant Providencia rettgeri, andhas a minimum inhibitory concentration of 125 [mu]g/mL and a minimum bactericidal concentration of 250 [mu]g/mL. The pulsatilla saponin A3 provided by the ivnention has an antibacterial effect on themulti-drug-resistant Providencia rettgeri, can relieve or solve the problem that the drug resistance of the multi-drug-resistant Providencia rettgeri is increased, and provides a theoretical basis forclinical antibacterial treatment and novel drug research and development.