Steel-fiber reinforced concrete slabs have good blast and spall resistance. In this study, compression and splitting tensile experiments were carried out to obtain the basic quasi-static mechanical properties of the steel-fiber concrete specimens and the influence of steel-fiber parameters was revealed. In-field explosion experiments were performed to study the dynamic responses and damage modes of the steel-fiber reinforced concrete slabs. Five typical spall damage modes were observed, the distribution law of the spalling fragments was obtained, and the influence of steel-fiber shape, length, length–diameter ratio and volume percentage on the spall performance were revealed. These results will provide a basis for the application of steel-fiber reinforced concrete slabs in protective structures.