We report a new structure self-assembled by ZnO nanolayers, nanoplatelets and microparticles under one-pot condition without surfactants. The structure shows tomato-like morphology with hexagonal symmetry. Selected area electron diffraction (SAED) analysis indicates that the assembly is highly oriented. However, considering the nonuniformity of the subunits, the structure is much different from the commonly observed ZnO mesocrystals. The growth of the complex structure in the solution is proposed to relate to the evolution of the supersaturations and segregation of the intrinsic defects.