Abstract: The Three functional fatty acids of 9-hydroxy-10E,12Z-octadecadienoic acid,9-oxo-10E,12Z-octadecadienoic acid and 9-oxo-10E,12E-octadecadienoic acid in tomato products were identified and analyzed by high performance liquid chromatography-mass spectrometry and high performance liquid chromatography. The column was Eclipse XDB-C₁₈(4.6 mm×250 mm,5 μm)and the mobile phase were made up of 0.005% trifluoroacetic acid water and 0.005% trifluoroacetic acid acetonitrile. The detection wavelength was set to 234,280 nm. The results showed that the three fatty acids were well separated within 20 min,with good repeatability(RSD ≤ 2.13%),high precision(RSD ≤ 0.70%),good stability(RSD ≤ 0.98%)and reliable recovery(RSD ≤ 3.38%). A rapid and accurate method for the determination of 9-hydroxy-10E,12Z-octadecadienoic acid,9-oxo-10E,12Z-octadecadienoic acid and 9-oxo-10E,12E-octadecadienoic acid in tomato products was established. The results showed that fresh tomato did not contain these three kinds of functional fatty acids,which only existed in tomato products,and the processing had the greater impact on the content. Furthermore,the 9-hydroxy-10E,12Z-octadecadienoic acid was discovered for first time in tomato products.