The invention relates to a method for reducing the content of erucic acid in radish seed oil. In a urea adduction method, the crystallization temperature is minus 20 DEG C-0 DEG C, the dosage of urea is 1-5 times that of mixed fatty acid, and the dosage of alcohol is 2-8 times that of the mixed fatty acid. The radish seed oil containing highly purified oleic acid, linoleic acid and linolenic acid and being low in erucic acid content is obtained. By means of further urea adduction operation, the content of erucic acid in the raw material radish seed oil is reduced to 1.25% from 34.30%, the content of linoleic acid is increased to 49.98% from 18.02%, the content of linolenic acid is increased to 33.49% from 9.94%, and the mass sum of linoleic acid and linolenic acid reaches 83.47% or more. The product can be used for producing drugs and healthcare products. The urea crystallization method is low in price, urea can be recycled, and the method has advantages compared with a traditional method; crystallization evaporation needs to be conducted for multiple times in the traditional method to achieve the effect, while the content of erucic acid can reach 5% or below of the national standard just though one-time urea adduction.