Abstract: In this paper, flexural experiments of RC tunnel liner with different curvature radius are firstly conducted to study the difference between strengthened RC straight beams and tunnel liners. It is shown in the experiments that the deflection-load curve can be divided into five stages. And the larger the radius of curvature is, the better of the reinforcement. However, within the range of 4 m ～ 6 m, influence of the difference of radius of curvature is difficult to reveal. Based on this understanding, the concept of the flexural capacity CFRP strengthened RC tunnel liners can be derived from a reduction of the flexural capacity of a CFRP strengthened RC straight beam. Thus a calculation method based on Chen ＆ Teng strength models for CFRP bonded to concert is proposed with the introduction of Reduction coefficientαc. Once the bonding strength dbic had been reduced toσdbic,c, the flexural capacity of CFRP strengthened RC tunnel liners can be obtained with the existing calculation method for CFRP strengthened RC straight beams. According to experimental results of this paper, recommended value ofαcis 0. 85 ± 0. 1.