Abstract: Bacterial efflux pump (EP) has caused serious antibiotic resistance, and consequently much attention has been paid to efflux pump inhibitors (EPIs) in recent years. EPIs could inhibit the efflux of drugs from bacteria and restore the susceptibility of drug-resistant bacteria to antibiotics. In this review, the structural features of several types of EPs were briefly introduced, and the current progress of synthetic and natural EPIs was summarized, hoping to provide researchers with new ideas to design or screen out new EPIs with higher inhibitory activity. Meanwhile, for more accurate and comprehensive screening and evaluation of EPIs and their clinical effects, research methods for EPIs and standardization of their antimicrobial susceptibility testing (AST) were also proposed