The invention belongs to the technical field of analytical chemistry, and particularly relates to a method for simultaneously determining the concentrations of eight antituberculous drugs in plasma by adopting a liquid chromatography-mass spectrometry method, wherein the eight antituberculous drugs comprise rifudine, chlorphenazine, levofloxacin, clarithromycin, sulfimide, p-aminosalicylic acid, moxifloxacin and amikacin. According to the method, the characteristics of hydrophilic and hydrophobic compounds are considered, protein precipitation is carried out by utilizing ACN:MEOH:45%TCA, the extraction rate of the hydrophilic compound AMK is improved, 20% of ACN, 0.2% of FA and 1% of HFBA are used as diluents, and the retention time of the hydrophilic compound AMK is prolonged by adding the HFBA. The method is high in sensitivity, strong in specificity and wide in linear range, can be used for qualitative and quantitative analysis of to-be-detected substances with unknown concentrations in plasma of tuberculosis patients, is simple and rapid to operate, does not need an extraction and volatilization process, and can meet the characteristics of urgent clinical treatment drug monitoring tasks and high requirements on detection time. The detection system provided by the invention provides a new technical platform for tuberculosis patient treatment drug monitoring, and is easy to popularize and apply.