An experiment study was conducted on the flexural behavior of reinforced concrete beam strengthened by Polyvinyl Alcohol-Engineered Cementitious Composite (PVA-ECC) mortar subjected to secondary load. Based on the comparison between test results of seven beams reinforced by PVA-ECC steel mesh and one general beam, the effect of once-loading extent and height of reinforcement at the side of RC beam on the flexural strength and deflections capacity was investigated. Beams were reinforced with U-shape, and the crack distribution, load-max deflection, strain development of concrete and steel, etc. were measured. Test results have indicated that PVA-ECC steel mesh technology is an efficient method to reinforce RC beam, which can markedly increase the load-bearing capacity, section stiffness and crack-resisting behavior. In addition，when the height of reinforcement at the side of RC beam is half of the beam's height，the load-capability of reinforced RC beam changes slightly compared with the full height of reinforcement R