Abstract: Ground penetrating radar detection technology, with its advantages of non-destructive, portable, and efficient, has been widely applied in the field of detecting tunnel lining void defects. However, its data interpretation still heavily relies on manual experience, affecting the accuracy of void identification.To improve the accuracy of identifying tunnel lining void defects, this paper establishes a data analysis method to assist in void identification based on the propagation characteristics of Ground penetrating radar electromagnetic waves in the lining and voids. This method is validated through a radar detection case study of a shield tunnel project, demonstrating its applicability. The research results show that: (1) at depths of 0.41 m, 0.45 m, and 0.50 m in the lined cavity area, the mean values of radar reflection wave amplitude are 2.1 times, 1.9 times, and 1.5 times the mean value of normal background amplitude, respectively. The attenuation rate of radar reflection wave amplitude accelerates with increasing depth, effectively characterizing the features of lined cavity defects; (2) the void range and depth determined with the help of amplitude curves are highly consistent with the actual void location drilling detection results; (3) by suppressing interference signals in the detection environment and selecting high-frequency antennas that meet the detection depth requirements, the quality of detection data can be significantly improved.This study provides an effective complementary means for Ground penetrating radar detection of tunnel lining void defects.