Abstract：It is usual to use Fourier spectrum analysis to process ground penetrating radar signal，but the effect is not always as good as expected. Complex signal analysis is a new method to process signal. It owns high precision and high distinguishing ability. It can distinguish weak signal in deep place and determine the abnormal place by using several parameters together. Complex signal analysis and Fourier spectrum analysis are compared in the processing of signals of the cases of solution cavities and a lake. It is shown that the former is better than the latter in that the pictures obtained by the former reflect the abnormal more distinctly and accurately. The boundary surface of mud silting of different time under the lake and the solution cavities are distinct after the processing of complex signal analysis.
