The improved DES (degradation degree, degradation extent and safety degree) comprehensive evaluation system based on DERU (degradation degree, degradation extent, relevancy and urgency) method is mainly used to evaluate the periodic inspection of operation highway tunnel structures. The indexes system, including the target layer, criterion layer and index layer, is firstly established. The indexes of D (degradation degree), E (degradation extent) and S (safety degree) of tunnel components are adopted as evaluation indexes of index layer; and then the corresponding determining standards and weights are proposed as well. The process for the different evaluation steps, including section evaluation, singletube evaluation and twintube evaluation, is established. The indexes of CI (condition index), PI (priority index) and S′L′ (equivalent safety degree length) are applied to determine the technical conditions of tunnel structures based on the periodic inspection results. Meanwhile, the evaluation results can be analyzed and graded according to the given methods and standards. The DES method can provide more intensive information to improve the efficiency of management, inspection and maintenance work for operation highway tunnels.