Background: Brain metastases (BMs) are a common and serious complication of non-small cell lung cancer (NSCLC). Whole-brain radiotherapy (WBRT), surgery, and molecular targeted therapy are usually used to treat NSCLC with BM. Chemotherapeutic options for BM are limited by tumor resistance, ineffective agents, and the blood-brain barrier. Pemetrexed/cisplatin is the preferred chemotherapy in nonsquamous NSCLC, but the efficacy of this treatment for nonsquamous NSCLC with BM is uncertain. Methods: We present a case of nonsquamous NSCLC with asymptomatic BM presenting with irritating cough and right shoulder back pain (unknown sensitizing epidermal growth factor receptor mutations or anaplastic lymphoma kinase). Results: He benefited from administration of first-line chemotherapy of pemetrexed/cisplatin. Partial remission was achieved in the primary lesion of the lungs and BM lesion. He was further given 3 cycles of pemetrexed monotherapy and WBRT. Complete remission was further achieved in BM lesion. Conclusion: The findings of clinical trials and theoretical studies about the current pemetrexed/cisplatin in the treatment of nonsquamous NSCLC with BM are also summarized to provide a reference for the application of pemetrexed/cisplatin in nonsquamous NSCLC with BM. Whether or not pemetrexed/cisplatin is definitely effective in nonsquamous NSCLC with BM must be proven by subsequent phase III clinical trials.