The invention discloses a judgment method of mixed crystal defect types of cable steel wire rod crystal grains and belongs to the technical field of steel rolling. The method comprises the steps of sampling and analyzing a defect part of a cable steel wire rod to obtain a mixed crystal defect type with the following characteristics. According to the characteristics, (1) the corroded edge of the cable steel wire rod has large crystal grains, the crystal grain grade ranges from the grade 0 to the grade 3, and the average diameter of the crystal grains reaches 1 mm or above; (II) the crystal grain size grade of middle columnar crystals generated after the cable steel wire rod is corroded reaches the grade 1-4, and the average crystal grain diameter stays in a range from 1 mm to 0.5 mm; (III)the crystal grain size grade of a circle of large crystal grains on the periphery of the cable steel wire rod after corrosion reaches the grade 3-5, wherein the large crystal grains are in an equiaxedcrystal shape, and the average diameter of the crystal grains stays in a range from 0.1 mm to 0.5 mm. According to the judgment method, the link causing generation of mixed crystal defects of the crystal grains of the cable steel wire rod is quickly determined through the detected mixed crystal defect types, so that targeted quality improvement and control measures are adopted from the aspects ofa source heating process and a rolling process, unqualified products are decreased, and the number of degradation or judgment revoking is reduced.