Prestressed UHPC strengthening technology was proposed to achieve a more efficient and durable strengthening for damaged RC structures. In order to investigate the effect of prestressed UHPC strengthening tech? nology on flexural behavior of RC beams, normal section bending tests were carried out on two damaged RC strength? ened beams (Reinforced-UHPC Strengthened Beam，RUB and Prestressed-UHPC Strengthened Beam，PUB) and one unstrengthened contrast RC beam (Reinforced Concrete Beam，RCB). Among strengthened beams, RUB was strengthened by the reinforced UHPC layer, and PUB was strengthened by the prestressed UHPC layer. The experi? mental results showed that all test beams showed conventional bending failure, and the flexural behavior of RC beams was significantly improved after being strengthened. The flexural strengthening efficiency of the prestressed UHPC layer was higher than that of the reinforced UHPC layer. The prestressed UHPC layer improved the stress state of the structure and further inhibited the formation and development of cracks. In addition, the better tensile performance of the prestressed UHPC layer made the flexural stiffness and ultimate bearing capacity of RC beams further improved. Compared with RUB, the cracking load and ultimate bearing capacity of PUB were increased by 89.2% and 36.9%,respectively. Also, a calculation formula of ultimate bearing capacity of prestressed UHPC strengthened beam was proposed, and the calculation results were in good agreement with the experimental results.