The invention discloses a method for degrading OTA (Ochratoxin A) through irradiation. The method comprises the following steps of performing drip washing on samples to be degraded with clean water, and performing drying until the water content is smaller than or equal to 10%; performing grinding to obtain granules of which the size is 20mm, placing the obtained granules in an ethanol solution of which the volume concentration is 70%, performing soaking for 2h, and performing water bath ultrasonic treatment for 5min, wherein the temperature of water bath is 30 DEG C or below; performing gamma irradiation on the samples to be degraded, wherein the irradiation dose is 4kGy; detecting the concentration of the Ochratoxin A in the samples to be degraded, and if the concentration of the Ochratoxin A in the samples to be degraded is smaller than or equal to 5[mu]g/Kg, determining the samples to be degraded to be qualified; and if the concentration of the Ochratoxin A in the samples to be degraded is greater than 5mug/Kg, performing gamma irradiation on the samples to be degraded until the concentration of the Ochratoxin A in the samples to be degraded is smaller than or equal to 5mug/Kg, wherein the irradiation dose is 5-10kGy. Through the adoption of the method disclosed by the invention, not only can the Ochratoxin A in corn and corn products be degraded efficiently, but also nutrient components of the corn and nutrient products cannot be destroyed.