Density function theory (DFT) at the B3LYP/6-311++G(2d) (5D, 7F) level of theory was calculated to predict the geometry structures, total energy and net charges of four kinds of dynamic isomer molecules of 2-aminino-5 mercapto-1,3,4-thiadizole (AMT for short). The fact that the atoms in four kinds of dynamic AMT isomer molecules lie in a plane and one kind of AMT is most stable is approved. The results also indicate that the pentagon ring in four kinds of dynamic AMT isomer molecules are aromatics, and the AMTc and Cu corrosion mitigation film produces as a result of the bonds form one by one of the covalent bond of Cu(I) with 7N atom in AMTc and the coordinate bond of Cu with 2S atom in ATMc. The resonant vibration frequencies and IR intensity for the four kinds of dynamic isomer of AMT are also calculated and their IR spectra are shown.