In order to investigate the shear resistance performance of double-T-shaped steel-concrete composite beams (DTSCB), three DTSCB specimens were designed and manufactured with concrete slab width and steel plate thickness as parameters, based on the test results of shear-mid-span deflection curve, shear-relative slip curve and strain distribution, The influence of structural parameters on the bearing capacity and deformation capacity of the composite beam was studied. An ABAQUS finite element model was established and validated by comparing with the experimental results to verify the accuracy of the model. The influence of different shear span ratios on the shear resistance of the steel beam, concrete slab, and wing plate with different structural parameters was simulated, and an expression for shear resistance was established. The results show that the limit shear span ratios for diagonal compression failure, shear failure, and bending failure of the composite beam are 1 and 3, respectively. When the shear span ratio is 1-3, the steel plate takes up about 70% of the shear resistance. The accuracy of the shear resistance calculation formula established is higher than that of the current code.