Abstract: The traditional external bonded carbon fiber reinforced polymer (CFRP) composite strengthening technique has no means of making full use of the material property and has limited strengthening effect. While prestressed CFRP strengthening technique could redeem this deficiency and have become the emphasis of research in the field of CFRP strengthening technique currently. An equipment which is used to the pretension of the CFRP plate have been invented and 8 flexural members strengthened with external bonded prestressed CFRP plates have been tested to investigate the capability of the prestressed CFRP plate as well as the deformation at operational phase and ductility and utilization efficiency of CFRP plate. The experimental results indicates that the prestressed CFRP plate could significantly improve cracking load and yield load, decrease deformation at operational phase and make use of the most of the characteristic of carbon fiber material, and that the structural ductility could satisfy the requirement of engineering after careful design.