Terahertz time-domain spectroscopy (THz-TDS) is used to investigate the spectra properties of the wheat kernel with various deterioration degrees in the frequency range of 0.2～1.6 THz. The absorption coefficient and refractive index of normal, worm-eaten, moldy and sprouting wheat kernel were calculated. Comparison of the experimental data, clearly indicates that changes in the absorption coefficient and refractive index are recorded, different wheat samples have different optical parameters. The absorption coefficient of normal wheat sample is more obvious and higher than others; refractive index increases as the frequency increases. THz-TDS can be employed to evaluate the quality of wheat kernel nondestructively. The results show that THz-TDS is a promising and new experimental method for quality analyses and control for agricultural production detection. This study will provide an important guidance for nondestructive detecting the quality of stored-grain.