The structural features of metal-organic frameworks (MOFs) can be analyzed based on the network structure (net) topology, composed of nodes and linkers. The connectivity and site symmetry of a node are probably the most important factors affecting the net topology of MOFs. Many MOFs with multiple nodes of different connectivity and site symmetry have complicated net topologies. However, the underlying net topology of some complicated MOFs could be analyzed using a hierarchical simplification approach. The underlying net topology of complicated MOFs with multi-connected nodes could be analyzed using a metal-organic polyhedron composed of multiple nodes as either a secondary building unit or a tertiary building unit. The simplified net topology provides better insight into the structural features of the complicated MOF structures and could be utilized in designing new MOF structures with known and/or unprecedented net topologies.