High　dispersive　and　well-defined　spherical　zirconia　nanocrystallites　were　synthesized　by　the　self-assembly　of　a　cationic　surfactant　under　the　hydrothermal　conditions.　Thermogravimetry-differential　scanning　calorimetry,　Fourier　transform　infrared　spectroscope,　X-ray　diffraction,　transmission　electron　microscope,　ultraviolet-visible　spectroscope,　and　N2　adsorption-desorption　analysis　were　used　for　the　structural　characterization.　The　results　show　that　the　cationic　surfactant　has　a　distinctly　direct　effect　on　the　formation　of　zirconia　nanocrystallites.　The　prepared　sample　exhibits　good　dispersion　with　a　tetragonal　phase　as　the　main　phase.　The　average　nanocrystal　size　is　about　15　nm　after　calcination　at　500°C.