Plant hormone Abscisic Acid (ABA) is a small molecule of an organic signal produced by the plant's own metabolism and can produce an obvious physiological effect to the plant itself in very low concentrations. ABA is one of the five endogenous hormones in plants, named for its ability to promote leaf shedding and mainly exists in the plant's withered leaves, roots, seeds etc. Because of its ability to regulate plant growth, ABA has a great prospect of agricultural engineering. However, the concentration of ABA in plants is deficient, so the detection of ultra-low concentration is the key to the application of ABA. As for the detection of ABA, there are many detection methods reported in the literature, but as far as we know, the theoretical and experimental studies on ABA by Raman spectroscopy have not been reported. Raman spectral technology has the advantages of simple sample pretreatment, fast analysis speed, low requirements for the detection personnel, and more suitable for in-situ and in-situ detection. Therefore, the experimental and mechanistic study of ABA Raman spectroscopy can provide a reliable basis for detecting and identifying plant hormones. In this paper, the molecular structure of ABA was optimized by software Gaussian09 and GaussView5. 0, and the molecular energy level, Front orbit, Raman spectrum, Infrared spectrum and Nuclear magnetic resonance spectrum of ABA were calculated. In order to verify the accuracy of theoretical calculation, the IR, Raman, SERS and NMR spectra of ABA molecules were tested. The results show that: ABA Raman characteristic peak theory calculated value at 616, 1 056, 1 272 and 1 689 cm^-1, experimental measured Raman characteristic peak in 612, 1 048, 1 272, 1 635 cm^-1, SERS experiment to obtain the characteristics peak is located at 598, 1 032, 1 268, 1 625 cm^-1, the theoretical calculation and experimental results are in good agreement. At the same time, the infrared and Raman peaks of ABA were identified in the range of 400~4 000 cm^-1, and the molecular oscillation modes of the ABA producing Raman spectrum at the corresponding Raman frequency shift were pointed out. The most substantial Raman peak of 1 635 cm^-1 was mainly caused by the stretching motion of the C=C bond and the C—C bond of ABA molecules, among which the stretching vibration of the C=C bond caused the most intense Raman scattering. Finally, atomic attribution and relative atomic displacement were analyzed, and the molecular structure of ABA was further studied according to comparing the calculation with the experimental nuclear magnetic resonance spectrum of ABA. What had done in the paper provided some experimental reference and theoretical basis for the trace detection of ABA.