Significant pharmacokinetic variation occurs in critically ill patients, leading to underexposure to antibiotics and poor prognosis. In this study, we developed a simple, sensitive, and fast liquid chromatography tandem mass spectrometry (LCMS/MS) platform for the simultaneous quantification of 8 antibacterial and 2 antifungal drugs, which is optimally suited for clinically efficient, real-time therapeutic drug monitoring (TDM). Multiple reaction monitoring (MRM) mass spectrometry was used in this method, and samples were prepared via protein precipitation with methanol. Chromatographic separation was accomplished on a BGIU Column-U02 (2.1x50 mm, 3 µm), with six stable isotopes and one analog as an internal standard. The overall turnaround time of the assay was 5 minutes. All the drugs tested (piperacillin, cefoperazone, meropenem, levofloxacin, moxifloxacin, daptomycin, linezolid, vancomycin, fluconazole and voriconazole) were linear in the test concentration range (r ≥ 0.9900), the accuracy was 95 %-111 %, the precision variation coefficient was greater than or equal to 10 %, the lower limit of quantitation was 0.31-7.51 mg/L, and the coefficient of variation of the matrix factor was less than 10 %. The recovery rates ranged from 85 % to 115 %, and the antibiotics were stable at 4°C and -20°C for 6 days, with an offset of greater than or equal to 15 %. This method was successfully applied to routine TDM in 252 elderly critically ill patients.