The present invention relates to a transition metal oxide/multi-walled carbon nanotube nanocomposite and its preparation method, and particularly to a nanocomposite prepared in a composite form of an electron-transmitting and stress-relaxing one-dimensional multi-walled carbon nanotube (MWCNT) and a high-capacity-enabling zero-dimensional nanopowder-type transition metal oxide, where a transition metal oxide prepared by urea synthesis is uniformly dispersed in a carbon nanotube by a surfactant, and its preparation method.Therefore, a process of preparing a nanocomposite herein is simple and can be easily applied to a large-scale production, while enabling the manufacture of uniform-sized nanocomposites even at a relatively low temperature. Thus prepared nanocomposite can be applied to an electrochemical device such as a lithium secondary battery and a super capacitor.