Abstract: Six initially loaded reinforced concrete (RC) beams with epoxy-bonded carbon fiberglass reinforced plastic (CFRP) sheets and two RC beams were experimentally investigated. The failure mechanism of RC beams strengthened with externally bonded CFRP sheets is analyzed. The effect of load history on flexural capacity is studied. The results generally indicate that the flexural strength of the repaired beams is increased. If the initial load is basically the same, the ultimate strength of reinforced concrete beams strengthened with CFRP sheets is almost the same regardless of load history at the time of strengthening. At the same time, an analytical solution is performed to testify the experimental results. The analytical results are in good agreement with those of experiments. A design method is proposed based on the experimental data.