Abstract: A method for simultaneous detection of 2-alkylcyclobutanones was established by gas chromatography-triple quadrupole mass spectrometry (GC-QqQ-MS/MS). Samples were dissolved by n-hexane, purified by ProElut Silica extraction column. The results show that 2-dodecylcyclobutanone(2-DCB), 2-tetradecylcyclobutanone(2-TCB) are well separated from matrix interference peaks. The peak area against concentration shows good linear relationship in the concentration of 0.005—1.0 mg/L, the linear correlation coefficients (R²) are greater than 0.999. Addition of 0.01, 0.05 and 0.10 mg/kg levels of 2-DCB and 2-TCB in fat-containing function food products, the average recovery ranges from 85.6% to 97.1%, the relative standard deviations (RSDs) are less than 7.0 % (n=6), and the limit of quantification is 5 μg/kg. The method is simple, time-saving, high sensitivity and good stability for real samples analysis，which can provide a theoretical basis for the detection of irradiated markers in the fat-containing function food.