The invention relates to a method for detecting monocytelike myeloid-derived suppressor cells in human peripheral blood. Used antibodies comprise an antibody APC anti-human CD33 (a), an antibody PE anti-human CD15 (b), an antibody PE-CF594 anti-human HLA-DR (c), an antibody APC-H7 anti-human CD14 (d), an antibody PE-Cy7 anti-human CD45 (e), and an antibody FITC anti-mouse CD11b (f). A flow type sample solution is prepared; the ratio of mo-MDSCs in the flow type sample solution is detected by a flow cytometer. For the detection of mo-MDSCs, the clear number screening range and specific screening range are given. The method has the advantages that the detection is simple, the operation is convenient, and the detection time is short; only a trace amount of peripheral blood sample markers is required, the cost is low, and the method is suitable for being widely popularized; the peripheral blood samples of 151 testing persons are respectively detected by the method; the detected mo-MDSCs ratio values are obviously different in different populations, and the ratio in a breast cancer patient is obviously higher than the ratio in a healthy person and a breast benign tumor patient; the detection results are calculated and analyzed by Graphpad Prism 6 software via a computer, P is smaller than 0.05, the statistic meaning is realized, and the results are scientific and credible.