Provided is a method of preparing a complex of a transition metal oxide and carbon nanotube. The method includes (a) dispersing carbon nanotube powder in a solvent, (b) mixing the dispersion with a transition metal salt, and (c) synthesizing a complex of transition metal oxide and carbon nanotube by applying microwave to the mixed solution. The method may considerably reduce the time required to synthesize the complex. In the complex of transition metal oxide and carbon nanotube prepared by the method, the transition metal oxide may be stacked on the surface of the carbon nanotube in the size of a nanoparticle, and may enhance charge/discharge characteristics when being applied to a lithium secondary battery as an anode material.