A rapid,simple and sensitive method based on high performance liquid chromatography-tandem mass spectrometry（HPLC-MS/MS） with an electrospray ionization（ESI） source was presented for the analysis of folic acid in various fortified food products（i.e.juice,rice,liquid infant milk,powder infant milk,biscuit and jelly）.Sensitivity and specificity of this method allowed three important results to be achieved:firstly,developing a rapid sample pretreatment that minimizes the analyte exposition to light,air and heat,eliminating any step of extract concentration and protection by aluminum foil;secondly adding BHT（butylated hydroxytoluene） as antioxidant;Finally,adding methotrexate as the internal standard.Effects of extraction conditions of different matrixes on recoveries were investigated.The sample was separated on a Waters HSS T3 column using methanol-10 mmol/L ammonium acetate（pH 6.3） as mobile phase by gradient elution,and analysed by MS with internal standard under multi-reaction monitoring（MRM） mode via positive electrospray ionization.The method indicated that the calibration curve showed a good linear relationship in the range of 0.05-100 ng/mL,with quantitation limits of 0.01-0.5 mg/kg in different matrixes.The recoveries were in the range of 72.0%-109%,with RSDs of 3.8%-11.8%.With the advantages of easy sample handling,high sensitivity and good precision,the method could meet the requirements for determination of folic acid.