Objective To establish a method for the determination of trace selenium （Se） in wheat flour by inductively coupled plasma mass spectrometry （ICP-MS）.Methods The wheat flour samples were processed by microwave digestion method， and cesium （74Ge） was used as internal standard. Different concentrations of monoethanol were added into the internal standard as sensitizers to determine the most appropriate sensitizer concentration. The anti-interference ability of helium collision mode and oxygen reaction pool mode was investigated to determine the optimal conditions for the determination of trace selenium in wheat flour by ICP-MS.Results 1% n-butanol was used as sensitizer， and the sensitizing efficiency and background equivalent concentration of Se were the best. The concentration was selected between 0.25-10.0 μg/L to draw the standard curve， the correlation coefficient r was 0.999 5， the detection limit was 0.001 mg/kg， the RSD of wheat flour sample was 1.37%， the average recovery rates of low， medium and high concentrations of selenium were 96.5%， 97.4% and 96.5% respectively. The results of GBW10045a GSB-23a Hu’nan rice quality control samples were satisfactory.Conclusion By using 1% n-butanol （v/v） as internal standard， the ICP-MS method for the determination of Se in wheat flour has the advantages of high sensitivity， accuracy and good repeatability， and is suitable for the determination of trace Se in wheat flour.