Objective To observe the clinical significance of myeloid-derived suppressor cells (MDSCs) on epithelial ovarian cancer. Methods A total of 203 patients with epithelial ovarian cancer admitted to Jiangxi Provincial People′s Hospital from January 2019 to January 2021 were selected as the study group, and 115 healthy volunteers were selected as the control group. 5 ml peripheral venous blood of the two groups was collected and the expression level of MDSCs characterized by CD33+HLA-DR-/low was detected by flow cytometry. The patients in the study group were divided into a good prognosis group(162 cases)and a poor prognosis group(41 cases)according to the prognostic outcome.The expression levels of CD33+HLA-DR-/low MDSCs were compared between the two groups, and the clinical value of CD33+HLA-DR-/low MDSCs expression in predicting the prognosis of epithelial ovarian cancer was analyzed by receiver operating characteristic(ROC) curve. The correlation between the expression level of MDSCs and clinical indicators and prognosis of epithelial ovarian cancer was analyzed based on the age, tumor stage, tumor size, differentiation degree and pathological type of the patients in the study group. Results The expression level of CD33+HLA-DR-/low MDSCs in the study group was higher than that in the control group, the difference was statistically significant (P＜0.05). The expression level of CD33+HLA-DR -/low MDSCs was higher in poor prognosis group than that in good prognosis group, the difference was statistically significant(P＜0.05).The area under the curve (AUC), specificity and sensitivity of expression level of CD33+HLA-DR-/low MDSCs were 0.713 (95%CI=0.646-0.775), 53.70% and 82.93% in judging the prognosis of epithelial ovarian cancer. The expression level of CD33 +HLA-DR -/low MDSCs had no correlation with age, tumor size and pathological type of patients (P＞0.05), but was positively correlated with tumor stage (r=0.458, P＜0.05) and was negatively correlated with the degree of differentiation(r=-0.342, P＜0.05). Conclusion MDSCs can have a high expression level in patients with epithelial ovarian cancer, which is closely related to the tumor stage and differentiation degree of patients, and can be used for early prognosis evaluation to guide clinical diagnosis and treatment.