The segregation of elements and the original particle boundary of powder metallurgy superalloy are the important factors affecting the material properties. Because the particle size is usually tens of microns, the traditional analysis method of composition distribution can not realize the fine characterization of the composition distribution at the original particle boundary of powder metallurgy superalloy. Microbeam X-ray fluorescence spectrometry (μ-XRF) is a non-destructive micro area composition distribution analysis technology developed in recent years. It can realize the rapid and high-resolution distribution analysis of elements in a wide range of materials. At present, it has been widely used in geology, archaeology, biology and other fields. However, there are still some difficulties in the quantitative distribution and characterization of complex block metal composition, which has not yet been applied in the powder metallurgy industry. In this study, the fluorescence spectrum behavior of each the element in superalloy was studied. The quantitative model of element was corrected by the type matching bulk standard sample of superalloy. The quantitative analysis method of composition distribution of Superalloy based on μ-XRF was established, which met the needs of powder metallurgy industry for fine quantitative characterization of powder boundary composition distribution on a large scale. The SPS powder superalloy samples treated by high purity cobalt alloying were taken as the research object. The quantitative statistical distribution of Ni, Co, Cr, Mo, W, Ta, Ti and Al in the powder sintered samples after different milling time were analyzed. The influence of different milling time on the composition distribution of the sintered samples was discussed. The results show that there are a large number of original particle boundaries, and the composition distribution is not uniform. The pure Co powder particles added by ball milling only exist in the outer layer of superalloy particles, resulting in the Co content at the edge of particles is significantly higher than that in the particle center. When the milling time is short, there are many Co enrichment areas at the boundary of the original particles. When the milling time is increased to 24 hours, due to the alloying of ultra-fine cobalt powder and superalloy in the process of mechanical mixing, the composition distribution uniformity of sintered samples is greatly improved, and the content of Co at the boundary of original particles decreases significantly, while the content of other elements increases. The results show that the diffusion of each element in this sample is obvious, which is helpful to the improvement of element segregation. Therefore, the preparation process of the powder metallurgy superalloy is improved. This method can also be used to characterize the composition distribution of other P/M industrial products and provide data support for the optimization of P/M process and the improvement of product quality.