In the previous study, we obtained the lowpolarity active ingredient Fr.2a from the chloroform extracts of Ziziphus jujuba Mill. var. spinosa fruits, and found that Fr.2a showed a wide range of synergistic antimicrobial effects when used in combination with a variety of antibiotics. On the basis of Fr.2a, the active components in other polar range of the chloroform extracts from Z. jujuba Mill. var. spinosa fruits were separated and purified by silica gel column chromatography, and the refined product Fr.B was obtained. Then, the composition of Fr.B was determined by GCMS, hydrogen nuclear magnetic resonance spectroscopy (1HNMR) and infrared spectroscopy (IR). The synergistic antibacterial spectrum and mechanism of Fr.B were determined by antimicrobial spectrum analysis and cell permeability analysis. The refined Fr.B was prepared into ointment by melting method. The synergistic effect of the ointment on antibiotics was evaluated by wound infection model in mice. The results were as follows: (1) the Fr.B component obtained by further refining the chloroform extracts of Z. jujuba Mill. var. spinosa fruits, mainly contained fatty acid compounds such as elaidic acid, oleic acid, cis10hexadecenol, palmitic acid and so on. (2) Fr.B showed extensive synergistic antibacterial action when combined with gentamicin, tobramycin, ampicillin, chloramphenicol, erythromycin, fusidic acid, nystatin, ketoconazole and amphotericin B, respectively. (3) Fr.B can enhance the permeability of bacterial cells by destroying the integrity of cell membrane and cell wall. (4) Fr.B can significantly enhance the bactericidal effect of erythromycin on methicillinresistant Staphylococcus aureus (MRSA) in vivo and in vitro, thereby improving the therapeutic effect of erythromycin on wound infections caused by MRSA strains. In conclusion, Fr.B obtained in this study has a broad spectrum of antimicrobial synergistic activity, which can enhance the efficacy of erythromycin in the treatment of wound drugresistant bacteria infection. This provides new ideas and solutions for overcoming microbial resistance to antibiotics.