Abstract: Lunar lava tube is one of the high value objects in lunar exploration. One of the important problems in the detection of lunar lava tube is the distinction between lunar surface clutter and lava tube echo. In this paper, the path attenuation speed of high-frequency electromagnetic wave and low-frequency electromagnetic wave is different in lunar soil, so there are different characteristics between the high and low frequency power ratio of lava tube and the high and low frequency power ratio of surface clutter. A method to determine the echo source by using the power ratio of high and low frequency electromagnetic wave is proposed. This paper mainly uses the pseudo-spectral time domain method, through the establishment of simulation system, modeling and simulation of the lunar surface, lunar strata and lunar lava tube. The simulation results show that it is an effective method to distinguish lunar surface clutter from lava tube echo by using the high and low frequency power ratio of echo. The power ratio of high and low frequency echo of lava tube and surface clutter is positively correlated with the buried depth of lava tube and the frequency ratio.