研究了4种乳糖的太赫兹光谱和红外光谱特性。利用太赫兹时域光谱 (THz-TDS) 测量了室温下α-乳糖，β-乳糖，α-乳糖一水合物，D（+）乳糖一水合物4种乳糖在0.2～2.6 THz范围内的吸收谱和折射率色散谱。实验表明在该频率范围这些物质有明显的吸收峰，且同种乳糖有无结晶水吸收峰差别很大，这种差别有望用于物质的鉴别。此外，利用傅里叶变换红外光谱（FTIR）测量得到1.8～10 THz之间这4种乳糖的吸收谱。利用Gauss 03软件进行了单分子量子化学模拟计算，得到0.2～10 THz频段这些乳糖的光谱特性，与实验结果进行比对，两者在一些峰位上有一定的吻合。同时，结合密度泛函理论(DFT)，对实验测量结果进行了一定的机理分析。

Terahertz (THz) and infrared spectra of four kinds of lactose are studied. THz absorption spectra and the dispersion of refractive index of α-lactose, β-lactose, α-lactose monohydrate, D(+) lactose monohydrate are obtained in the frequency range of 0.2～2.6 THz at room temperature by using of THz time-domain spectroscopy (THz-TDS). The experimental results show that there are the significant absorption peaks for these substances in this frequency range. These absorption peaks show a large difference in the presence or absence of crystallization water for the same lactose. This difference is expected to be used to identify these substances. In addition, the absorption spectrum of four lactose is also measured by the Fourier transform infrared spectroscopy (FTIR) within 1.8 and 10 THz. The spectral characteristics between 0.2 and 10 THz of four lactose are simulated based on the single molecular model by using of Gauss 03 software. Both of simulation and experimental results fit well at the position of absorption peaks. At the same time, the spectral characteristics of four lactose are analyzed based on the density functional theory (DFT). The mechanism of molecular motion shown from the experimental results is presented and analyzed.