Abstract: Objective To investigate the nutritional status of patients with adjuvant chemoradiotherapy after gastric cancer surgery and its correlation with side effects of chemoradiotherapy. Methods Totally 88 patients with adjuvant chemoradiotherapy after gastric cancer surgery from October 2015 to October 2018 in our hospitals were selected and divided into normal nutrition group(n=42)and risk nutritional group(n=46)according to the score of Nutritional Risk Scale(NRS2002). The adverse reactions such as myelosuppression, side effects of nervous system, blood system and gastrointestinal tract were recorded during radiotherapy and chemotherapy in both groups, and the adverse reactions were classified according to the World Health Organization(WHO)classification standard of chemotherapy related adverse reactions, and the correlation between the nutritional status of patients and the adverse reactions of chemoradiotherapy was analyzed. Results The incidence rates of myelosuppression, side effects of nervous system, blood system and gastrointestinal tract in the risk nutrition group were significantly higher than those in the normal nutrition group(P<0.05). Spearman's correlation analysis showed that nutritional status was negatively correlated with myelosuppression(r=-0.527, P=0.001), nervous system(r=-0.352, P=0.001), blood system(r=-0.430, P=0.001)and gastrointestinal tract(r=-0.380, P=0.001). Conclusion Malnutrition can increase the risk of side effects of postoperative adjuvant radiotherapy and chemotherapy for gastric cancer - and affect the patient's tolerance of follow-up treatment. Therefore, nutritional intervention should be strengthened during chemotherapy.