Based on original FEM/DEM coupling analysis method, a new model for blast simulation is implemented. The model considers increasment of the volume occupied by the gas and stable decrease in gas pressure with the expansion of cracks due to the blast gas embedding, and also takes into account the action of gas on the fissures linked at the explosion chamber. The limitation is overcome in the existing blasting model of FEM/DEM, where the pressure is only applied on the surface rock of blasting chamber without considering action of the embedded gas on the newly generated cracks. Meanwhile, a novel search algorithm of fracture network is proposed by compiling a simple recursive function for the search of complex fracture network; and a very simple method is used to handle the complex problem. Finally, a numerical example indicates that the improved FEM/DEM can simulate crack initiation and propagation of stress waves during explosion, showing a great potential of this method for the blast simulation.