A method of preparing a silicon oxide (Six)-carbon composite for a negative-electrode active material of a lithium secondary battery, includes mixing silicon (Si) particles and a polymer material with an organic solvent, thus preparing a mixture solution, optionally electrospinning the mixture solution thus preparing a composite having a one-dimensional structure, and heat-treating the mixture solution or the composite having a one-dimensional structure. The silicon oxide (SiOx)-carbon composite can reduce volume expansion upon lithium ion insertion and can increase ionic conductivity and electronic conductivity and thus can maintain high capacity, making it possible to apply it to a lithium ion battery to thus improve electrochemical characteristics of the battery.