The present invention provides an advanced oxidation system for the treatment of offensive odors and toxic substances of foundry waste, e.g., sand, and a treatment method using the same, which can effectively remove offensive odors and toxic substances produced during a sand reclamation process for reclamation of foundry waste. For this purpose, an advanced oxidation system for the treatment of offensive odors and toxic substances of foundry waste by implementing a spray device for spraying a diluted solution of hydrogen peroxide onto foundry waste; a stirring device for mixing the foundry waste with the diluted solution of hydrogen peroxide sprayed thereto; an ultraviolet irradiation device for activating the hydrogen peroxide mixed with the foundry waste to produce radicals; and a local exhaust system for collecting dust generated when the foundry waste is mixed with the hydrogen peroxide by the stirring device.