Provided is a preparation method of copper nanostructures, characterized in that a copper precursor including halide is reacted with polyethyleneimine (PEI) and a reducing agent in an aqueous solution. According to this method, the copper nanostructures may be easily prepared in a sphere, wire, or plate form, and high-quality copper nanostructures may be produced with a high production yield of 90% or more. This method is also appropriate for large-scale production.