Novel efficient biochar of Goldenberry peels (GBPMW-H3PO4) was prepared through a microwave-assisted phosphoric acid activation method. It was characterized and used for removing two beta-lactamase inhibitors, sulbactam (SAM, first listed in Japan in 1986) and avibactam (AVI, first listed in the U.S. in 2015), from aqueous solution. Characterization confirmed that GBPMW-H3PO4 displayed a high surface area (720.046m2 g-1), more abundant pore structure, smaller particle size, and higher thermal stability. The experimental results showed that the adsorption of the two antibiotics was a spontaneous, favorable, and endothermic process, highly dependent on solution pH. A contact time of 60 min assured equilibrium, and GBPMW-H3PO4 followed pseudo-first-order kinetics (R2=0.9950-0.9977). Furthermore, the adsorption capacities of GBPMW-H3PO4 for SAM and AVI were 211.86 and 198.81mg g-1, respectively, and the performance was better than that of unmodified biochar. Microscopically, the main mechanism could be explained by π-π electron donor-acceptor interaction, hydrogen bonding interaction, π-hydrogen bonding, hydrophobic interaction, and electrostatic interaction. The study demonstrates that the microwave-assisted H3PO4 activation method could produce biochar, and GBPMW-H3PO4 was confirmed to be a low-cost and high-efficiency adsorbent for removing beta-lactamase inhibitors from medical wastewater.