The ultra-high performance concrete which has high ductility and toughness, is widely used in the construction of new structures. The key feature of ultra-high performance concrete is that it has a very high potential in bearing strong loads such as impact loads or explosions. In this paper a 3D model of an ultra-high performance concrete slab is modeled and subjected to blast loading in LS-DYNA finite element software. To this end, different scenarios of blast loading are selected and the responses including the vertical displacement and the plastic strain contour of the slab are determined under each scenario. In this numerical model, the effect of strain rate on the dynamic behavior of materials is also considered. It is observed that when the slab is subjected to a shorter distance and stronger blast load, it first experiences the largest displacement and after that the displacement decreases and remains constant. However, in the case of exposure to a weaker blast load at a longer distance from the surface of the slab, the slab fluctuates relative to the initial position with an almost constant fluctuation period and has little displacements.