A method was developed for the determination of N，Na，Mg，P，Cl，K，Ca in milk powder by wavelength dispersive X-ray fluorescence spectrometric method with pressed powder pellets.Effects of experimental conditions，including X-ray tube Beryllium window thickness，current intensity of instrument，measurement time，and sample preparation，on the determination of nitrogen were studied.Different kinds of milk powder samples were chosen and determined firstly by reference methods，then calibration curves were drawn using both the milk powder samples with known contents and reference materials.To eliminate the effect，the theoretical α influence coefficient method was used to correct matrix effects.It was found that manual grinding could better realize the homogeneous treatment of the sample.Thickness of beryllium window was the main factor restricting the nitrogen determination，but influence of the current intensity of fluorescence intensity was limited.X-ray irradiation could cause milk powder browning，forming the color and smell similar to that of maillard reaction.Furthermore，internal protein also suffered severe damage，and multiple interference could make the contents of P，Cl，K，Ca change according to a certain rule.For nitrogen，limit of detection and RSD（n=9） were 900 mg/kg，29%，respectively，and for other elements，limits of detection and RSDs were less than 10 mg/kg，3.0%，respectively.The measurement results were consistent with the reference method.