In this study, in order to investigate the effect of the explosive mass on the wave propagation behavior of the explosion in the building and the free environment, the software of the finite element LS Dyna and the theory of grained law have been used. The Kinetic relations in free environment show that pressure variations in the first stage are influenced by distance, and are then influenced by the amount of explosives with a relatively less proportional ratio. Since these relationships are valid with the assumption of free environment, it's not possible to use an explosion inside a building. In this study, the effect of material mass on the amount of pressure inside a building has also been studied. In numerical simulation, using Eulerian-Lagrangian analysis, an explosive is placed inside a concrete building and the impact of the explosion caused by the explosion on building demolitions is investigated. The type of explosive H-6 and its mass is about 50 and 100 kilograms. The results show that the effect of the explosive mass in a free-explosion explosion is much more sensitive than the closed environment, due to the effect of reflection of the waves in the closed environment.