One patient with multiple primary malignant tumors (MPMTs) was treated at the Department of Oncology of Shanghai Pudong New Area People’s Hospital. Since the first diagnosis of breast cancer, patients have survived for more than 18 years. The patient, female, 45 years old, underwent surgery and postoperative chemotherapy on March 26, 2001 due to “the discovery of left breast mass for more than 3 months”. Review on May 19, 2002 suggested that malignant tumor may be considered in the right breast. Preoperative neoadjuvant chemotherapy was followed by surgical treatment, postoperative chemoradiotherapy and oral tamoxifen for 10 years until 2013.In December 2017, the patient was admitted to Shanghai Huashan hospital due to “chest tightness and shortness of breath for 1 week”. PET/CT examination suggested lung cancer, liver and bone metastasis. In January 2018, bronchial artery and hepatic artery perfusion chemotherapy and embolization were performed in the general surgery department of our hospital. The patient has been treated regularly with zoledronic acid for bone preservation. In March 2018, patients received no relevant genetic test after hepatic artery perfusion chemotherapy and embolization and took gefitinib orally until August 2018. Nodules in the lower lobe of the right lung and the upper lobe of the right lung were reduced, and the original low-density nodules in the liver were also significantly reduced. On October 18, 2018, the patient went to see a doctor for “interstitial discharge pink gross hematuria” and underwent cystoscopy under local anesthesia and biopsy. The biopsy pathology suggested that the patient had non-invasive low-level papillary urothelial carcinoma of the bladder. After surgery, gemcitabine was given 1 g bladder perfusion chemotherapy. On December 1, 2018, the patient was admitted to our hospital due to numbness of the right limb. The head CT of our hospital showed low-density shadows in the left parietal lobe and right temporo-occipital region, and the brain metastasis of the patient was considered. During the period of December 3, 2018 to June 21, 2019, the brain lesions of the patient were resolved and the liver lesions were significantly reduced after the treatment of whole-brain radiotherapy, oral Gefitinib, intravenous chemotherapy and oral AZD9291(blood test revealed EGFR T790M mutation). In this case, the time of PFS has not yet reached. The tumor markers decreased and the quality of life was good. The incidence of multiple primary malignancies is relatively low, involving many diseases and relatively difficult to treat. In terms of diagnosis, it is recommended to select pathological examination for new lesions to exclude the possibility of multiple primary lesions. The application of targeted drugs to target gene sensitive mutations is very important in the selection of treatment methods. Multi-disciplinary treatment (MDT) mode has the advantages of minimizing misdiagnosis and mistreatment of patients, shortening the waiting time for diagnosis and treatment, increasing the selectivity of treatment plan, and formulating the best treatment method.