The present invention provides a process for preparing Y-branched carbon nanotubes and the product thereby, Y-branched carbon nanotubes. More specifically, the present invention provides a process for preparing Y-branched carbon nanotubes, comprising: loading a catalyst on a carbon nanotube carrier; pre-treating the catalyst-loaded carbon nanotubes to have the catalyst bonded tightly to the surface of carbon nanotubes; and performing a synthetic reaction of carbon nanotubes using the obtained catalyst-loaded carbon nanotubes. According to the process of the present invention, Y-branched carbon nanotubes having at least one or more Y-junctions in various shapes can be prepared easily, simply and in bulk by utilizing the conventional facilities under the usual condition of process. Thus, the invention is promising industrially. The Y-branched carbon nanotubes of the invention hold great potential in regard of materials for electrodes, reinforcing agents for polymers, transistors and electrochemical products.