Based on Kelvin’s contact force calculation model, the conditions required for simulating the mechanical behavior of the porous materials consisting of spherical particles are analyzed, from which a new granular model construction method is proposed. In this model a seed position is stochastically generated in the complex solution domain; and then it is gradually expanded to fill the entire region. In the filling process a local Delaunay triangulation mesh control is used to generate new particles; and particle distance control in a complex geometry boundary is used to decide the relative position of a new generated particle. For particles near the model boundary, an optimized tolerance position and radius are calculated and filled, which enhances the coupling characteristic between boundary and the particles. Meanwhile, the pore position can be refilled to ensure that each particle is tangent with at least three particles in order to improve the coupling characteristic between model particles. Finally, arbitrary polygons are used to divide several materials. The model region will be simplified for judging whether the polygon point is in the polygon or not, which can simplify the setup process of complex model materials. The results show that the proposed method has small overlap between particles, high filling rate between particles, particle and boundary. The proposed method can decrease flying overflow phenomenon when the adhesive force between particles disappears, and can be used to model construction of random connected domain.