Nano-sized SiO_x/C composite with core–shell structure is prepared by a modified Stöber method. After heat-treatment, the O/Si ratio in SiO_x/C composite is near 1 and the core of SiO_x presents a structure composing of amorphous Si clusters and ordered SiO₂ domains. SiO_x/C composite anode shows high specific capacity (ca. 800mAhg⁻¹), excellent cycling stability, good rate-capability but low initial coulombic efficiency. Li₂O and Li₄SiO₄ may generate in the initial lithiation process, which, combining with the carbon shell, can buffer the volume change caused by the alloying of Si with Li, and thereby improving the cycling stability of electrode. The nano feature of SiO_x/C particle and the electronic conductive nature of carbon coating layer ensure the good rate-capability of SiO_x/C electrode.