Abstract An effective method is developed for modeling and characterization of two-phase composites using Voronoi diagram in the Laguerre geometry based on random close packing of spheres (RCP-LV). First, RCP is generated with two groups of spheres and each group has its own volume distribution. Then LV diagram is performed basing on the sphere packing to generate the grains of two phases, thus the model of two-phase composite is obtained. Because the model is based on the RCP, the grain volume distributions of the two phases are easily controlled by changing the volume distributions of two groups of spheres in RCP. Various geometrical and topological characterizations are conducted, yielding useful information of this kind of composite. This modeling method can be utilized in deep investigation of structure–property relations in two-phase composites.