Novel bulk ZnO porous nanosolids were pre- pared by a unique solvothermal hot-press method, using ZnO nanoparticles and several kinds of solvents as the start- ing materials. It was found from the experiments that ZnO nanoparticles underwent a “self-assembly process” under some specific hydrothermal hot-press conditions. As a result, some “nanoflowers” formed. The results showed that porous nanosolids with uniform pore diameters could be obtained when water distributed uniformly among the ZnO nanopar- ticles. On the contrary, if the uniformity of the distribution of water was poor, “nanoflowers” would appear in the wa- ter-rich region. It was also found that the photoluminescence of ZnO porous nanosolids was affected by the self-assembly phenomenon. In addition, the results also showed that, both the volume and diameters of the pores could be adjusted by changing either the hot-press temperature, pressure or the kinds of solvents.