Abstract: Lava tubes are one of the prime candidates for establishing extraterrestrial bases. To verify the feasibility of using ground-penetrating radar to detect lava tubes on extraterrestrial bodies, this paper first conducted a technical study to validate the detection of lava tubes using a 400 MHz ground-penetrating radar system on the Seventy-Two Caves and Wolong Cave in the Shishan Volcanic Group in Haikou, Hainan. It is found that the upper interface of the lava tube is clearly displayed when the depth of the tube is 2 m, and the radar image shows the upper and lower boundaries when the height is less than 3 meters. Additionally, the genetic algorithm is employed to inverse the dielectric constant of the lava tube’s wall. The reliability of the genetic algorithm in calculating the dielectric constant is validated through comparison with results obtained from the depth method and sample measurement. Furthermore, the analysis of samples establishes a simple relationship between porosity and dielectric constant. These findings are of significant importance for assessing the underground spatial distribution and wall stability of the lava tubes, providing a reference for future lunar base establishment.