The invention discloses a method for measuring contents of interstitial carbon atoms in material alpha-Fe systems by utilizing Snoek relaxation internal friction peaks. According to the method, two segregation coefficients k1 and k2 are introduced to represent interstitial carbon atoms segregated to dislocation and crystal boundary parts, so as to subtract the carbon atoms segregated to a defect part from the total carbon atoms, thereby finally obtaining a relatively correct k value. According to the method, influences, on the interstitial atoms, of dislocation and crystal boundary are considered, and segregation coefficients of the interstitial atoms at the dislocation and crystal boundary parts are introduced, so as to further correctly obtain a numerical relationship between interstitial atom content and Snoek relaxation internal friction peak strength, thereby more correctly utilizing internal friction test to measure the interstitial carbon atom content. According to the method, the carbon atoms segregated at the defect part are removed from the carbon atoms in the alpha-Fe system, the used data is more accurate, the obtained result is more correct and reliable, and internal friction test can be more correctly utilized to measure the contents of the interstitial carbon atoms.