Abstract: ¹⁴C, a radionuclide, which is widely used in all works of life, such as medical research and determination of PM2.5, has been realized autonomous production in China. It relied on imports, which was expensive and unstable supply in the past time. At present, Qinshan Nuclear Power has started ¹⁴C production to completely solve the problem of the serious shortage of ¹⁴C independent supply in China. Aluminum nitride powder is the main raw material for the preparation of ¹⁴C, whose elemental aluminum directly affects the safety and quality of ¹⁴C isotopic targets in nuclear reactors. Aluminum nitride is very stable in an inert high temperature environment. But a lot of elemental aluminum will react with water producing hydrogen in a high temperature environment which can result in the expansion of component rods or it will react with cladding tubes producing hydrogen embrittling effect, and these can affect the quality of ¹⁴C isotopic target. According to the characteristic of aluminum nitride insoluble in acid, this study researched different dissolution effect of elemental aluminum in aluminum nitride nano-powder by nitric acid, hydrochloric acid and sulfuric acid. It was found that the above mentioned acid can only dissolve a small amount of aluminum nitride powder, and there was a small amount of aluminum nitride powder suspending in solution, which would seriously interfere the determination of elemental aluminum. At present, microwave digestion, laser ablation, X-ray fluorescence and other methods are used to dissolve or determinate aluminum nitride, but they are not suitable for the determination of elemental aluminum. The determination of elemental aluminum is generally used in pharmaceutical, soil, tea and other samples, but most of the aluminum in the above samples exists as an impurity element, or aluminum is combined with organic matter, which is easy to separate from elemental aluminum. However, it is difficult to achieve complete separation of elemental aluminum(unbound elemental aluminum) and the aluminum nitride matrix in the aluminum nitride powder. This study used replacement reaction to selectively dissolve elemental aluminum. Then the suspended aluminum nitride powder was separated by filter membrane filter. By this method, it could solve the determination interference to elemental aluminum. This study established the determination of elemental aluminum in aluminum nitride nanoparticles by inductively coupled plasma mass spectrometer(ICP-MS), which has the advantages of low determination limit, high accuracy, fast determination speed and small matrix effect. This method’s linear range is 10-100 μg/g and the relative standard deviation is 3.8%(n=6). Using high purity alumina powder to verify the established determination method, the dissolution efficiency can reach 96%-98%.