The surface of steel fiber was modified by silane coupling agent (SCA), and the modified fiber was characterized by scanning electron microscopy and fourier transform infrared spectroscopy. The flexural properties and single-fiber pull-out properties of two SCA (KH560 and KH550) modified steel fiber cement-based composites were studied by bending tests and single-fiber pull-out tests. The results show that KH560-modified steel fiber can improve the early flexural strength and toughness of cement-based composites, single-fiber peak bonding stress and single-fiber pull-out energy. However, in later stages, KH560 deteriorates the steel fiber-matrix interface, which has a negative effect on flexural properties and single-fiber pull-out behavior. In contrast, KH550-modified fiber shows the opposite effect to that of KH560. The modified group with volume ratio of KH550 and KH560 of 5∶5 and 7∶3 can improve the early and late bending properties of steel fiber cement-based composites, and effectively improve the bonding performance of steel fiber-matrix interface. The composite SCA improves the roughness of steel fiber surface and facilitates chemical bonding at steel fiber-SCA-matrix interface. The composite SCA effectively improves the flexural strength and toughness of steel fiber cement-based composites.