Lung metastasis of Triple-negative breast cancer (TNBC) causes severe breath-related events and poor prognosis. Ruyiping (RYP), a traditional Chinese medicine prescription, is used to treat breast cancer lung metastasis in clinical practice. This study was to explore the anti-lung-metastatic activities and mechanism of RYP extract by regulating macrophage polarization. The results showed that RYP can inhibit the viability and induce the apoptosis of TNBC cells. In in vitro experiments, RYP significantly inhibited the invasion and migration ability of TNBC cells promoted by M2, the subtype of macrophage which increased TNBC metastasis related genes. In in vivo experiments, RYP reduced the TNBC progression and lung metastasis. M2/M1 ration in the lung and M2 in the tumor was reduced by RYP, as well as M2 master regulator Stat6. Therefore, RYP extract may exhibit anti-lung metastasis function by reducing M2 in both tumor and lung through reducing Stat6.Keywords: Lung metastasis; Macrophage polarization; Ruyiping extract; Triple negative breast cancer.