Breast cancer metastasis is the most common cause of cancer-related death in women. Thus, seeking targets of breast tumor cells is an attractive goal towards improving clinical treatment. The present study showed that CCL18 from tumor-associated macrophages could promote breast cancer metastasis via PITPNM3. In addition, we found that pachymic acid (PA) could dose-dependently inhibit migration and invasion of MDA-MB-231cells, with or without rCCL18 stimulation. Furthermore, evidence was obtained that PA could suppress the phosphorylation of PITPNM3 and the combination of CCL18 and PITPNM3. Therefore, we speculate that PA could inhibit breast cancer metastasis via PITPNM3.