In order to investigate the complex dynamic response of strain-hardening cement-based composites (SHCC), a specialized mechanical shear testing apparatus was employed in conjunction with a hydraulic testing machine and a newly designed split-Hopkinson tension bar (SHTB) for testing, with shear span and notch depth as the primary shear parameters. Shear tests were conducted on two sets of specimens with shear span of 2, 5 mm, and three sets of notch depth of 3, 5, 7 mm, to study the quasi-static and impact shear behavior of SHCC. Digital image correlation (DIC) was used to monitor deformation and crack evolution during the testing process. The research results reveal that shear span influences the shear behavior of SHCC. Shear span and notch depth can control the propagation of shear and tensile fractures, and by selecting an appropriate shear shape, dominant shear fracture of specimens can be achieved. Smaller shear span leads to higher shear forces and narrower areas of predominant shear crack propagation, weakening the material performance. Under both quasi-static and impact loading conditions, the 3 mm notch depth specimen exhibits higher self-confinement and higher fracture strength, displaying a mixed failure mode (compression-shear). On the other hand, the 7 mm notch depth specimen consistently demonstrates the most favorable shear fracture mode, characterized by vertical shear cracks, with shear fracture dominated by crack slip. Therefore, 7 mm notch depth specimen in gravity-loaded SHTB test can be used to accurately assess the shear characteristics of complex mineral-based materials. This study provides a theoretical basis for the optimization of cement-based composites performance.