Since peanut oil(PO) is more expensive than other seed oils,some PO is adulterated with other cheap seed oils,such as soybean oil,palm olein,cottonseed oil,corn oil and rapeseed oil.The conventional method for determining whether PO was adulterated is to detect the freezing point of oils.The proposed method for the determination of adulterants in PO was based on monitoring the change of absorbance when the sample was refrigerated.A special spectrophotometer was developed.A total of 10 kinds of POs from different suppliers were chosen and adulterated with other seed oils at the volume fraction levels ranging from 5％ to 30％.A total of 150 samples were analyzed by the proposed method and the results were satisfactory.