Abstract: The nanocrystalline copper bulk materials with different thickness were prepared by hot pressing method under different technological parameters and the used Cu nano-powders were obtained by flow-levitation method. The correlations between the grain size, density and structure with rigidity properties of nanocrystalline copper bulk were investigated by using XRD, SEM, balance and sclerometer. The results show that the hardness of thin nanocrystalline copper decreases as its grain size increasing, the relationship of which is accorded with Hall-Petch formula. The hardness value has a large difference at different parts of thick nanocrystalline copper bulk, which is mainly influenced by surface defect and the difference of grain size. The diversity of density is neglectable at the different parts of it.