The experimental study and finite element analysis of RC beams strengthened with CFRP board are introduced in this essay. Test research of six beams stuck with CFRP board on their tension faces has been carried out on rigidity by contrasting with three nonstrengthened beams. Three specimens are primary loading beams and the others are secondary loading beams, the calculating formula for the short-term rigidity on the section of concrete beams strengthened with CFRP board has been established. Calculation is carried out on short-term deflection of RC beams strengthened with CFRP board subjected to primary load and secondary load. The results indicate that the RC structure can be strengthened effectively by sticking with CFRP board, so that the expansion of crack and rigidity of beam can be controlled especially, and the experimental results compared with those predicted by the formula in resemblance.