The incidence of lung neuroendocrine carcinomas, which originate from lung neuroendocrine cells, is 1.35/100,000, among which mixed neuroendocrine carcinomas are very rare. Because of the heterogeneity and significant differences in sensitivity to treatments, there is no effective treatment, and the prognosis is poor. In this article, we report the diagnosis and treatment of a case of mixed neuroendocrine carcinoma of the lung in our hospital. During the treatment, the patients had significant myelosuppression after initial chemotherapy, but benefited from oral chemotherapy consisting of a combination of capecitabine and temozolomide (CAPTEM). The report was approved by the affiliated Cancer Hospital of Shandong University.