Abstract: The shear-span ratio is an important factor affecting the shear performance of concrete members. This work conducted 16 beams with different section sizes (maximum beam height is 1200 mm) and different shear span ratios (\lambda = 1.0, 1.5, 2.0). The shear failure behavior of CFRP-strengthened reinforced concrete beams without stirrups under different shear-span ratios and cross-section sizes was studied, and the quantitative influence of shear-span ratio on shear strength and size effect of CFRP-strengthened reinforced concrete beams without stirrups was revealed. The rationality and accuracy of the established size effect law was compared and analyzed. It was found that shear failure and the debonding of CFRP sheets occurred in the U-type CFRP bonded reinforced concrete beams. The shear-span ratio has little effect on the size effect of the shear strength of the strengthened beam, but the value of the shear strength has a great effect. For example, in a 1200 mm depth strengthened-beam, with the increase of shear-span ratio (from 1.0 to 2.0), compared with the beam with a shear-span ratio of 1.0, the shear capacity is reduced by 27% and 55%. In addition, the nominal shear strength of beams with different shear-span ratios decreases 43% with increasing beam size. Moreover, the size effect law of shear strength proposed in the previous study could describe the quantitative influence of shear-span ratio on the shear strength of CFRP-strengthened concrete beams with different cross-sectional dimensions accurately.