Object-oriented and property-oriented concept lattices are constructed based on rough set theory. In this paper, a uniform mathematical model-concept granular computing system is first established by mappings on two complete lattices. In this framework, object-oriented and property-oriented concept granular computing systems are introduced for property-oriented and object-oriented concept lattices, respectively. Properties of these two kinds of concept granular computing systems are discussed. And relationships between a concept lattice and a corresponding concept granular computing system are also investigated.