OBJECTIVE： To develop a method for simultaneous determination of 12 nonsteroidal anti-inflammatory drugs （NSAIDs） illegally added into antirheumatic TCM preparations. METHODS： UPLC-MS/MS was adopted. The determination was performed on Hypersil Golden C18 column with mobile phase consisted of 5 mmol/L ammonium formate solution-methanol （gradient elution） at the flow rate of 0.2 mL/min. The column temperature was 40 ℃， and the sample size was 2 μL. A tandem quadrupole mass spectrometer equipped with electrospray ionization source was used in positive-negative ion mode： curtain gas of 25 kPa， atomizing gas of 60 kPa， auxiliary gas of 55 kPa， electrospray voltage of 4 500 V， ion source temperature of 650 ℃.The multiple reaction monitoring mode was performed. RESULTS： The linear ranges of acetaminophen， acetylsalicylic acid， aminopyrine， meloxicam， ibuprofen， naproxen， lam acid， nimesulide， diclofenac， indomethacin， ketoprofen and celecoxib were 0.01-2.0 μg/mL（r＝0.995 6），0.05-5.0 μg/mL（r＝0.997 6），0.01-2.0 μg/mL（r＝0.998 7），0.02-5.0 μg/mL（r＝0.995 0），0.02-5.0 μg/mL（r＝0.995 3），0.02-5.0 μg/mL（r＝0.996 5），0.05-5.0 μg/mL（r＝0.995 4），0.02-5.0 μg/mL（r＝0.996 0），0.05-5.0 μg/mL（r＝0.995 9），0.02-5.0 μg/mL（r＝0.995 7），0.02-5.0 μg/mL（r＝0.996 8），0.01-2.0 μg/mL（r＝0.998 7）， respectively. The limits of quantitation were no more than 0.20 mg/g， and the limits of detection were no more than 0.05 mg/g. RSDs of precision， stability and reproducibility tests were all lower than 5.0％. The recoveries were 80.8％-114.2％（RSD was 3.85％-7.32％，n＝9）. CONCLUSIONS： The established method is simple， accurate， stable and reproducible， and can be used for simultaneous determination of 12 NSAIDs illegally added into antirheumatic TCM preparations.