Co(OH)2 nanosheets, which obtained from Polyvinyl Pyrrolidone (PVP) improved solution-phase synthesis, can be transformed to porous Co3O4 nanoplates by solid-state crystal reconstruction during heat treatment in air. Transmission electron microscopy (TEM) indicates that the transformation process and final crystal structure are strongly dependent on the temperature of heat treatment. When the temperature is increased to 500 °C, the mesoporous and single-crystal Co3O4 nanoplates with an average size of around 1 μm can be obtained by solid-state diffusion, coalescence and following orientational alignment. Electrochemical tests show that the lithium storage performance of porous Co3O4 nanoplates is associated more closely with its structural aspects than its morphology and size factors. The obtained plate-like Co3O4 mesocrystals exhibit low initial irreversible capacity and superior cycling performance due to its micrometer size, porous and robust single-crystal structure. Considering the improved electrochemical performance, simple and large scale synthesis, the obtained 2D Co3O4 mesocrystals should be suitable as anode materials for high performance lithium-ion batteries.