At present, the time domain dielectric spectroscopy is mainly used to analyze thin liquids or materials composed of molecular orderly substances. The various relaxation processes need to be unrelated or be superposed linearly. But it will be clearly limited when the method is applied to the complex heterogeneous mixture analysis. In order to widen its scope of application, the analysis method is improved in this paper by using the wavelet transform. Through the analysis of the oil-water mixture, the experimental results show that the time domain dielectric spectroscopy based on wavelet transform can not only offer the whole spectral information but exhibit the time domain and frequency domain information of various components. Therefore, the analysis method of time domain dielectric spectroscopy based on wavelet transform can be used to analyze complex heterogeneous mixtures.