【Objective】The shear tests of four rectangular reinforced concrete (RC) beams were conducted to investigate the effects of the end-anchorage method and preloading on the shear behavior of the carbon fiber reinforced polymer (CFRP)-strengthened RC beams.【Method】The failure mode, load-deflection curve, characteristic load, strain developments of the stirrup and CFRP were analyzed. Finally, the shear capacity of the specimens was predicted using the existing calculation methods for the shear capacity of the CFRP-strengthened RC beam. 【Result】The test results show that the using U-shaped CFRP strengthening can significantly enhance the shear behavior of RC beams under the reliable end-anchorage. The shear strengthening effect is significantly affected by the end-anchorage methods. The mechanical anchorage is obviously superior to the CFRP sheet anchorage. Compared with the unstrengthened beam, the shear capacity of the strengthened beam with the mechanical anchorage increases by about 60%, whereas that with the CFRP sheet anchorage only increases by 9.8%. The preloading significantly decreases the cracking load of the strengthened beams, but does not affect the shear capacity.【Conclusion】The research results can provide reference for the engineering application of shear strengthening of RC beams with CFRP sheets.