Objective: To retrospectively analyze the efficacy of pemetrexed combined with platinum in the treatment of breast cancer patients with lung metastases and the relevant prognosis factor. Methods: The clinical data of 44 cases of breast cancer with lung metastasis from July 2011 to July 2016 were retrospectively analyzed. According to the different treatment regimens, the short- and long-term efficacy were analyzed. The clinical features, treatment regimens and prognosis of 44 patients with breast cancer were analyzed by Cox regression analysis and Cox multivariate model. Results: The total effective rate was 61.4% (27/44) in 44 patients with breast cancer after lung metastases. The clinical efficacy of pemetrexed combined with platinum group (group B) was better than that of gemcitabine combined with chemotherapy group (group A), (76.0%, 19/25 vs 42.0%, 8/19), the difference was statistically significant (P=0.023). The toxicity of blood, nausea and vomiting occurred in both groups. The incidence of anemia, leukopenia, thrombocytopenia, nausea and vomiting and oral mucositis in group B were significantly lower than those in group A, the difference was statistically significant (P<0.05). The median follow-up period was 22.5 months (6 to 60 months), the median progression-free survival (PFS) was 14 (95% CI 6.0–22.1) months, median lung metastases-overall survival (LM-OS) was 41 (95% CI 30.9–50.1) months, PFS was 49.2% at 2 years after lung metastasis, and 41.4% in 5 years after lung metastasis. There was no significant difference between PFS and LM-OS in both groups. The results of univariate and multivariate analysis showed that pathologic type, clinical stage and clinical effect after rescue treatment were prognostic risk factors. Conclusion: The prognosis of lung metastases in breast cancer is poor, especially triple-negative, stage IV breast cancer with lung metastases and progress after treatment. The use of pemetrexed combined with platinum-based chemotherapy has a good short-term effect in the treatment of only lung metastasis or lung metastasis with bone metastases in patients with advanced breast cancer with less adverse events, but the patient’s long-term prognosis has not been significantly improved.