针对使用透射式测量系统难以提取太赫兹波段高吸收样品电磁参数的难题，采用反射式时域光谱系统分别测量了极性液体和非极性液体的时域光谱。通过时域有限积分算法对太赫兹波在样品中的传播特性进行建模，并使用高斯混合模型重新构建反射光谱，从噪声中恢复了原始的太赫兹时域信号，解决了反射式系统信号易受干扰导致的电磁参数发生伪波动的问题。实验结果表明，使用恢复信号计算得到的水和液体石蜡在0.4 THz～2 THz波段的折射率和消光系数，与使用原始信号计算得到的结果相比，有效地消除了波动现象，去趋势波动分析（detrended fluctuation analysis, DFA）标度指数较之原始信号计算值分别上升了7%、3%、29%、31%，验证了该方法的有效性和正确性。

Aiming at the difficulty in extracting the electromagnetic parameters of highly absorbing samples by using the transmission measurement system, the time-domain spectrum of polar and non-polar liquids were measured by the reflection time-domain spectroscopy system. The propagation characteristics of terahertz wave in the sample were modeled by finite integration time domain algorithm, and the reflection spectrum was reconstructed by using the Gaussian mixture model to restore the original terahertz time-domain signal from the noise, which solved the false fluctuations in electromagnetic parameters caused by the interference of signal in reflection system. The experimental results show that compared with the results calculated by using the original signal, the refractive index and extinction coefficient of water and liquid paraffin in the 0.4 THz~2 THz band calculated by using the restored signal, effectively eliminate the false fluctuations, and the detrended fluctuation analysis (DFA) scale index is increased by 7%, 3%, 29%, and 31%, respectively, which verifies the validity and correctness of the method.