Objective To explore the influence of enteral nutrition support treatment on nutritional status, immune function and adverse effects in patients with gastric and esophageal carcinoma after chemotherapy. Methods Patients with gastric and esophageal cancer receiving chemotherapy in our department from January 2017 to January 2018 were successively collected. The patients were randomly divided into the enteral nutrition group and routine dietary group. According to the degree of obstruction, nutritional structure and intake of the patients, all of the patients received nutrition advice. Besides, enteral nutrition preparation was given two days before the beginning of chemotherapy and one week after the end of chemotherapy for the patients in enteral nutrition group. The indicators of nutritional status, biochemical, immune function and adverse effects (blood system and gastrointestinal side effects) were observed between the two groups. Results 56 patients were enrolled, among which, the enteral nutrition group 29, the normal diet group 26, the male 36, the female 20. After chemotherapy, nutritional status in the enteral nutrition group improved obviously. The level of white blood cells, serum albumin, hemoglobin, and CD4+/CD8+ in enteral nutrition group were increased significantly (P<0.05). Besides, the 3~4 degrees blood system adverse effects decreased significantly (P<0.05). Conclusions Enteral nutrition support can improve the nutritional status and immune function of patients with gastric esophageal cancer during chemotherapy, reduce the adverse effects after chemotherapy, and help to improve the quality of life of patients. Due to the small number of cases, the further studies are needed.