OBJECTIVE To explore the effect of peripheral blood regulatory T cells and inflammatory factors on prediction of postoperative infection in breast cancer patients. METHODS The patients who received breast cancer resection in Suizhou Central Hospital from Jan 2014 to Dec 2019 were recruited as the study objects, 44 patients who had postoperative infection were assigned as the infection group, 88 patients who did not have postoperative infection were set as the non-infection group.The levels of inflammatory factors high sensitivity C-reactive protein(hs-CRP), interleukin-6(IL-6), interleukin-10(IL-10) and peripheral blood regulatory T cells [CD_4∼+, CD_(25)∼+, CD_(127)∼((low))] were observed and compared between the two groups of patients, and the clin. value of the indexes in diagnosis of the postoperative infection was analyzed after the surgery for 5 days. RESULTS The levels of hs-CRP, IL-6 and IL-10 of the infection group were resp.(8.87±3.15)mg/dL,(18.32±5.07)pg/mL and(7.41±1.26)pg/mL after the surgery for 5 days, significantly higher than those of the non-infection group(P<0.05).The levels of CD_4∼+,CD_(25)∼+ and CD_(127)∼((low)) of the infection group were resp.(1.41±0.35)%,(1.33±0.41)% and(1.52±0.58)%, significantly lower than those of the non-infection group(P<0.05).The accuracy of the inflammatory factors was 84.36% in prediction of the postoperative infection in the breast cancer patients, the specificity 69.17%; the accuracy of the peripheral blood regulatory T cells was 73.21% in prediction of the postoperative infection, the specificity 80.09%; the accuracy, specificity and sensitivity of the joint detection of the two types of indexes were remarkably higher than those of the detection of single index. CONCLUSION The levels of inflammatory factors of the breast cancer patients are elevated after the breast cancer resection, while the levels of peripheral blood regulatory T cells are reduced, and the accuracy, sensitivity and specific of the two types of indexes are high in prediction of the postoperative infection in the breast cancer patients.