In this study, we successfully prepare SnO(2) nanoparticles inside the pore channels of CMK-3 ordered mesoporous carbon via sonochemical method. The content of SnO(2) is 17 wt % calculated according to the energy-dispersive X-ray spectroscopy (EDS) result. CMK-3 with 17 wt % loading of SnO(2) nanoparticles has a large specific surface area and pore volume. Electrochemical performance demonstrates that the ordered SnO(2)/CMK-3 nanocomposites electrode possesses higher reversible capacity and cycling stability than that of original CMK-3 electrode. Moreover, the ordered SnO(2)/CMK-3 nanocomposites electrode also exhibits high capacity at higher charge/discharge rate. The improved electrochemical performance is attributed to the nanometer-sized SnO(2) formed inside CMK-3 and the large surface area of the mesopores (3.4 nm) in which the SnO(2) nanoparticles are formed.