Terahertz frequency resolution is an important factor affecting substance identification,but the presence of the device reflection within the terahertz time domain spectroscopy systems,causes the presence of a plurality of reflection peaks in the ref-erence and measurement signals with low frequency resolution,because of the length truncation of time domain signal.In order to remove the influence of the reflection peak,this paper proposes a method based on empirical mode decomposition to remove the time domain reflection peak,to improve the terahertz frequency resolution.The time domain reflection peaks are positioned by correlation with the real terahertz peak,calculating the reflection peak upper and lower envelope and an average,obtaining in-trinsic mode functions,and alternating reflection peaks with intrinsic mode functions,the effective length of the time domain sig-nal is increased to improve the terahertz frequency resolution.Water vapor in the air terahertz transmission spectroscopy results show that this method can self adaptively remove a plurality of reflection peaks and has good repairing effect on the terahertz time-domain signal;the frequency resolution is increased by 1 2 times;and the useful information of absorption spectrum is not lost;the absorption peak position and the number is consistent with real spectrum;the terahertz spectrum ability to identify is well preserved.%太赫兹频率分辨率是影响物质鉴别的重要因素，但是由于太赫兹时域光谱系统中存在器件反射，使得参考信号和测量信号出现多个反射峰，时域信号长度截断导致频率分辨率很低。为了去除反射峰的影响，提出基于经验模态分解去除时域反射峰，从而提高太赫兹频率分辨率的方法。通过与太赫兹主峰的互相关定位时域反射峰，计算反射峰的上下包络和求平均值，获取本征模函数并代替反射峰，增加时域信号有效长度，提高太赫兹频域分辨率。空气中水蒸汽的太赫兹透射谱实验结果表明，该方法具有自适应去除多个反射峰的能力，对太赫兹时域信号修复效果良好，频率分辨率提高了12倍，而且未丢失有用的吸收谱信息，吸收峰的位置和个数与真实谱一致，很好地保留了太赫兹谱的鉴别能力。
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