The application of steel wire mesh and polymer mortar composites to the surface of reinforced concrete (RC) members as external reinforcement is a promising and recent new technique for strengthening and rehabilitating damaged concrete elements. This new technique has many advantages of resistance to fire, corrosion, ageing, and rapid construction speed. Test results indicated that the overall flexural behaviour of strengthened beam can be divided into three stages: precracking stage, cracking stage, and failure stage. Furthermore, a moment deflection model is developed based on the assumption of plane sections remains plane under load. The flexural behaviour of the strengthened specimens subjected to a four-point bending test was addressed by using transformed section approach. The suggested model was verified using the test data of 6 strengthened beams, and good agreement between experiment and prediction values is achieved.