A method of high performance liquid chromatography-quadrupole/electrostatic field orbitrap high resolution mass spectrometry（HPLC-Q/Orbitrap MS） was developed to determine 4-methylimidazole（4-MI） and 2-methylimidazole（2-MI） in soy sauce.Samples were diluted with deionized water,and then purified with a MCX solid phase extraction column.After eluted with 5% ammoniated methanol,the eluent was evaporated to dryness at 45 ℃ under nitrogen.The residue was dissolved with a mixture of acetonitrile and water in specific proportion through a vortex mixing.The obtained mixture was then filtered through a polytetrafluoroethylene（PTFE） membrane with pore size of 0.45 μm.The analytes were separated on an Agilent HILIC Plus（2.1 mm×100 mm,3.5 μm） column by isocratic elution with acetonitrile -5.0 mmol/L ammonium acetate（80∶20，by volume） as mobile phase.Full scan experiments were performed over the range of m/z 50-100 in positive mode to determine the accurate mass of analytes.The parent ion was used for quantitation based on the external standard.Under the optimal conditions,4-MI and 2-MI were well separated.The detection limits for 4-MI and 2-MI were 2.5 mg/kg.Good linearities were obtained in the range of 25-500 ng/mL with their correlation coefficients higher than 0.99.The average recoveries at three spiked levels were in the range of 78.3%-95.7% with relative standard deviations（RSDs） not more than 9.4%.The proposed method was simple and sensitive,and could meet the requirements for the determination of 4-MI and 2-MI in all kinds of soy sauce,contribute to regulate the production of soy sauce and the addition of caramel colours.