To scientifically evaluate the health of the lining structure through a comprehensive analysis of the structural disease of railway tunnel lining, a graded evaluation system for the structural state of railway tunnel lining was established based on extension theory and combined weight values and in line with the principles of developing an evaluation system of railway tunnel lining structure. The system refined the calculation process for graded evaluation. To obtain the weight values, by combining the entropy method with Delphi method, a method of weight assignment taking into account different grades of evaluation was proposed. On such a basis, an evaluation was given to the lining structure state in Lakeside No.1 Tunnel, Xiaosi No.1 Tunnel, and Kuishi Tunnel in the Jinhua-Wenzhou freight line. According to the results, the eigenvalues of the comprehensive grade of the lining structure in the three tunnels are 3.246, 2.544 and 2.535, respectively. The results agree well with the actual tunnel conditions, which verifies the reliability and effectiveness of the method.