The present invention relates to a method for preparing silicon-based active material particles for a secondary battery and silicon-based active material particles. The method for preparing silicon-based active material particles according to an embodiment of the present invention comprises the steps of: providing silicon powder; dispersing the silicon powder into an oxidant solvent to provide a mixture prior to grinding; fine-graining the silicon powder by applying mechanical compression and shear stress to the silicon powder in the mixture prior to grinding to produce silicon particles; producing a layer of chemical oxidation on the fine-grained silicon particles with the oxidant solvent while applying mechanical compression and shear stress to produce silicon-based active material particles; and drying the resulting product comprising the silicon-based active material particles to yield silicon-based active material particles.