Abstract: A new composite material named Fiber Reinforced Polymer is used in the strengthening field of civil engineering widely.This new strengthened technology using prestress(called prestressed reinforcement) can availably develop the strong capacity of FRP.In order to know the mechanical characteristics of RC beam in bending capacity,experimental study and theoretical analysis are combined in the process of research.Twelve concrete beams reinforced by CFRP bar,BFRP bar and strand were made.The reinforced effects including cracking load,yielded load,ultimate load,development of crack,improvement on rigidity and destructive mode are compared and researched.