Many flexural or tensile reinforced concrete members must be crack-free or the crack widths must be within specified limit value at service load levels. Presently, there are a number of structure members cannot satisfy its designed serviceability, due to the degradation of structural materials (due to durability problems) or by an increase in design loads. The use of bonding CFRP sheets on the side surfaces for strengthening or repair existing RC beamsis proposed to investigate the first crack strength and the cracking characteristics of RC beams. In order to verify the effectiveness of this application, experimental tests on six strengthened beams and one control beamhad been carried out. Experimental results demonstrated that this appears a promising technique both on improving the first crackstrength and on suppressing the crack width.