Abstract: LC-MS/MS was applied to the determination of 8 kinds of synthetic colorants, including tartrazinein, amaranth, ponceau 4R, sunset yellow, fancy red, EDS, food red 14 and azorubine in food. The solid or semi-solid samples were dissolved with C2H5OH-NH3 (aq.) and H2O (70+1+29) solution, and the filtrate liquor was evaporated to dryness. The residue was dissolved with water and used for LC-MS/MS determination, using Waters Atlantis dC18 column (2.1 mm×150 mm, 5 μm) as chromatographic column, and a mixture of methanol and 10 mmol·L-1 ammonium acetate with the different ratios as mobile phase for gradient elution. Positive electrospray ionization mode was used in the MS/MS detection. Linear relationships between values of peak area and mass concentration of the 8 synthetic colorants were obtained in the range within 50 μg·L-1 with their detection limits (3S/N) in the range of 0.003-0.020 mg·kg-1. The proposed method was used to the determination of the 8 synthetic colorants in food, giving values of recovery in the range of 83.0%-112.0% with RSD′s (n=6) less than 5%.