Abstract: UHPLC-MS/MS was applied to the determination of 5 photoinitiators (PIs) in food plastic packaging materials and their migration rules were researched. Agilent Eclipse Plus C₁₈ chromatographic column was used as stationary phase, and the mixture of 1 g·L^-1 ammonium acetate solution and acetonitrile mixed in different ratios was used as mobile phase in gradient elution. ESI⁺ and selected ion monitoring mode were adopted in MS/MS. Lower limits of determination (10S/N) of the method were in the range of 1.38-5.56 μg·dm^-2. Values of recovery found by standard addition method were in the range of 77.5%-95.0%, with values of RSD's (n=6) in the range of 0.81%-8.9%. The 5 PIs held different migration ability in different food stimulants and they exhibited a more migration behaviors in 30 g·L^-1 acetic acid solution. The migration rates in different food plastic packaging materials of 5 PIs were correlated to barrier property of packaging materials.