We quantitatively analyzed the content of the element Ni in the national standard soil samples by the method of X-ray fluorescence spectroscopy through using EDXRF metal experimental platform in ambient environment of the laboratory. Studying the characteristics of X-ray fluorescence of element Ni in the experiment，the calibration curve of element Ni was measured by using the adding internal standard method and the method of how to select the internal standard element was analysed according to the experimental results. The experimental results demonstrate that the matrix suitable element can be selected as the internal standard element to analyse the soil samples; using Pb Lα line, Cu, Fe and Kα lines as internal standard lines, the relative deviation of element from the standard value is 6.24%, 5.24% and 5.22%, which indicates that selecting the appropriate characteristic line of the matrix major element as the internal standard line can effectively improve measurement accuracy of the results.