By combining the ANSYS-based finite element method with the test, the changes of the flexural bearing capacity and shear bearing capacity of specimens with the shear-span ratio are analyzed, and the influence of the shear-span ratio on the failure mode of specimens is investigated respectively under single-point and two-point symmetric loading on the midspan. The results show that (1) the debonding failure of steel plates occurs only when the shear connection are not complete; (2) under the single-point ( two-point symmetric) loading on the midspan with a shear-span ratio of less than 7.5 (7) , the flexural bearing capacity of section is more sufficient than the shear bearing capacity, so the shear failure of specimens occurs; (3) when the shear span ratio is between 7.5(7) and 10(9) , neither the flexural bearing capacity of section nor the shear bearing capacity is sufficient, so the bending shear failure of specimens occurs; and (4) when the shear span ratio is more than 10(9) , the flexural bearing capacity of section is more insufficient than the shear bearing capacity, so the bending failure of specimens occurs.