A high performance liquid chromatography-tandem mass spectrometric(HPLC-MS/MS) method was established for the simultaneous determination of 4 kinds of optional components(choline,L-carnitine,taurine and inositol) in infant formula milk powder.After dissolution with warm water,the protein in sample was precipitated with zinc acetate and potassium ferrocyanide.The supernatant was separated on an HSS T3 column,then detected by MS/MS under MRM mode,and quantified by the internal and external standard methods.Under the optimized conditions,the calibration curves were linear in the ranges of 0.01-2.0 mg/L for choline and L-carnitine,and 0.1-2.0 mg/L for taurine and inositol,with correlation coefficients larger than 0.997.The detection limits of the method were 1.5 mg/kg for choline and L-carnitine,and 15 mg/kg for taurine and inositol,respectively.The mean recoveries were in the range of 87.5%-102.4%with relative standard deviations(RSDs,n=6) of 3.0%-7.3%.The method,with the advantages of high sensitivity,good purification effect and quantitative accuracy,is applicable for the detection of choline,L-carnitine,taurine and inositol in infant formula milk powder.