Abstract: Pb(Zr0.52Ti0.48)O3 (PZT) nano-powder was prepared efficiently by hydrothermal method, with the characteristics of good dispersion, small grain, high sintering activity and so on. From the theory of electrolyte solution and the idea of crystallography, the particularity of physical and chemical environment for preparing PZT nano-powder is discussed. The driving force of forming nuclei and crystal growth of PZT nano-crystal are analyzed.