Abstract: A method was established for simultaneous detection of 19 sulfonamides in seafood by multi-plug filtration cleanup (m-PFC) method with liquid chromatography-tandem mass spectrometry (LC-MS/MS). The samples were extracted with formic acid acetonitrile after being fully wetted with water. QuEChERS salt pack were added to the system to separate into organic and aqueous phases. The upper fraction was purified on an m-PFC column before analysis by LC-MS/MS, the samples were analyzed in multi-reaction monitoring (MRM) mode and quantify by the matrix-matched external standard method. The results showed that 19 sulfonamides had good linearity in the range of 1~100 μg/L with determination coefficients higher than 0.997. The detection limits were in the range of 0.005~0.15 μg/kg, and the quantitation limits were 0.01~0.41 μg/kg. At three spiked levels of 10, 20 and 100 μg/kg, the average recoveries of 19 sulfonamides ranged from 70.0% to 114.1%, with relative standard deviations (RSDs) of 0.5%~9.4%. This method is simple, highly sensitive and reproducible, and is suitable for the detection of sulfonamides in seafood.