The isotopically labeled products are obtained by substituting one or more atoms in the compound with its isotopes or other easily identifiable nuclides. Stable isotopes refer to isotopes whose nuclear structure is stable and will not decay, such as 15N, 18O, etc. Radioisotopes, such as 3H, 14C, 32p, 131I, etc, are isotopes whose nuclear instability will decay and emit α-rays, β-rays or γ-rays. In isotope labeling, there are many methods to detect the existence of labeled isotopes. According to their mass, vibrational modes and radioactive decay, the mass difference of isotope can be detected by mass spectrometry, and the difference of vibration mode of isotope can be detected by the infrared spectrum. Nuclear magnetic resonance (NMR) is used to detect atoms with different gyromagnetic ratios. Radioactive decay can be detected by the ionization chamber or gel autoradiography. Isotope labeling has the advantages of high sensitivity, simple location, and accurate quantification, so isotope modification has been paid more and more attention in the fields of medicine and biochemistry.