Density gradient ultracentrifugarion (DGU) separation method was estabilished to obtain monodispersed colloidal nanostructures.Such separation method was demonstrated as a versatile method for acquisition of monodispersed colloidal nanoparticles which are hard to be synthesized.This separation method was applicable to both aqueous (polar) and organic (non-polar) solvents system and NPs with different size, density and morphology can be separated.