A matrix matching-external standard quantification method was established for the simultaneous determination of the content of six kinds of benzotriazole ultraviolet absorbers in polymethyl methacrylate (PMMA) plastics. The samples were cut up, extracted using ultrasonic extraction with a mixed solvent of toluene and dichloromethane(volume ratio 1∶1), and then precipitated with n-hexane. After purification and filtration by 0.22 μm organic filter membrane, TG-5 capillary column was used with unsplit stream sampling. The samples were imported by full scan mode, determined by gas chromatography and mass spectrometer, and quantified by matrix matching and external standard method. The extraction solvent, time and matrix effect were analyzed, and the mass spectrum parameters were optimized. Six kinds of benzotriazole ultraviolet absorbers could be separated well and quantified accurately. The recoveries were 85.4%~104.0%, the relative standard deviations were 0.7%~5.1%, the correlation coefficients were above 0.996 0, and the detection limits were 0.7~1.6 mg/kg. The method is simple and efficient, using matrix-matched external standard quantification, which provides higher accuracy, and is suitable for the accurate determination of the content of six ultraviolet absorbers in PMMA plastic.