Abstract: The inspection and maintenance of the civil structure of operating highway tunnels in karst areas is of great significance for ensuring the safe operation of tunnels. By conducting investigation and statistical research on the defect characteristics of a group of tunnel cases in karst areas of Guangxi, and analyzing the needs of tunnel maintenance work, a highway tunnel civil structure inspection and evaluation system was constructed based on the DERU method. The lining, pavement, and drainage system are regarded as evaluation indicators for tunnel components, and the technical condition index values of tunnel structures are calculated by using D, E, R, and U values.On this basis, a suitable detection system was developed and applied in conjunction with practical engineering cases.