The miniaturization of metal-organic-framework (MOF) crystals to the nanoscale brings enhanced or novel properties and fulfils specific application needs. The focus here is on a kind of nanoMOF with special configurations and outstanding properties - the hollow structure. Firstly recent advances on the synthesis of MOF hollow nanostructures are introduced. Then, a novel approach based on a heterometallic system is highlighted, by which the facile synthesis of well-defined hollow MOF structures with high complexity is achieved. Moreover, MOF hollow nanostructures are emphasized as hosts/shell materials to incorporate functional catalysts that show dramatically enhanced performances in gas-involved reactions due to their inherent gasabsorption/storage properties.