The structures of five kinds of millet from Shandong, Shanxi, Hebei and other provinces were studied by mid infrared (abbreviation: MIR) spectroscopy. The results showed that the infrared absorption modes of millet mainly include OH stretching vibration mode (νOH), CH3 asymmetrical stretching vibration mode (νasCH3), CH2 asymmetrical stretching vibration mode (νasCH2), CH2 symmetrical stretching vibration mode (νsCH2), CH stretching vibration mode (νCH), C==O stretching vibration mode (νC==O), protein amide Ⅰ band mode (νamide-Ⅰ), protein amide Ⅱ band mode (νamide-Ⅱ), protein amide Ⅲ band mode (νamide-Ⅲ) and C—O stretching vibration mode (νC—O). Furthermore, the corresponding synchronous 2D-MIR spectroscopy of millet, including νasCH3-2d, νasCH2-2d, νsCH2-2d and νCH-2d, have some differences, which can quickly and accurately identify the five kinds of millets. This paper expanded the research scope of three-step MIR spectroscopy in structure and rapid identification of high-quality millet.