Abstract: A method of liquid chromatography tandem mass spectrometry (LC-MS/MS) was developed for the detection of migration levels of fluorescent whitening agent (FWA) 184 and 393 in food contact plastic container. Through the experiment investigation and analysis, the fat simulant (95% alcohol) was confirmed as soaking solution. The migration rule of analytes in two different migration temperatures (low storage condition of 5 ℃ and room storage condition of 40 ℃) and varied migration time were studied by LC-MS/MS, and the corresponding migration equation was established. The results show that the linearity ranges from 0.03 μg/L to 20 μg/L with the correlation coefficients of 0.999 2 and 0.999 6 for FWA 184 and FWA 393, respectively， and the detection limits are all 0.01 μg/L. The recoveries range from 91.1% to 105.3% and RSD (n=6) range from 2.7% to 6.4% at the spiked levels of 0.03, 0.3 and 3 μg/L. The migration levels of FWA 184 and FWA 393 are increased with the increase of storage temperature and storage time. The method is sensitive, accurate, and suits for determining the migration of FWA184 and FWA393 in food contact plastic container.