Objective To investigate the effects of Shenqi Fuzheng Injection combined with nutritional support on tolerance, nutritional status，cellular immunity，Th1/Th2 and peripheral blood circulating tumor cells in patients with locally advanced nasopharyngeal carcinoma undergoing radiotherapy and chemotherapy. Method A total of 120 patients with locally advanced nasopharyngeal carcinoma who received induction chemoradiotherapy in our hospital from January 2021 to January 2023 were selected and divided into three groups by random number table method. Group A (40 cases) received radiotherapy and chemotherapy alone, group B (40 cases) received nutritional support during radiotherapy and chemotherapy, and group C (40 cases) received intravenous infusion of Shenqi Fuzheng injection combined with nutritional support during radiotherapy and chemotherapy. The completion of treatment, adverse reactions and efficacy of radiotherapy in the three groups were observed, and the changes and differences of nutritional status，cellular immunity，Th1/Th2 and peripheral blood circulating tumor cells before and after intervention were compared. Results All patients in the three groups completed radiotherapy and chemotherapy. The proportion of radiotherapy interruption ≥5d and total course ≥45d in group C was lower than that in group A (P<0.017), and the synchronous completion rate was higher than that in group A (P<0.017). The incidence of oral mucositis and leukopenia with grade Ⅲ or above was lower than that in group A (P<0.017). There was no significant difference in the efficacy of induced chemoradiotherapy among the three groups (P>0.05). The CD3+ T cells, CD4+ T cells, CD4+/ CD8+, ALB, PA, HGB, TRF, number of Th1, Th1/Th2 and peripheral blood circulating tumor cells in group A was decreased compared with before treatment (P<0.05), Th2 was increased compared with before treatment (P<0.05). CD3+ T cells, CD4+ T cells, CD4+/ CD8+, ALB, PA, HGB, TRF, Th1 and Th1/Th2 in groups B and C were increased after treatment compared with before treatment (P<0.05)，and the number of circulating hematoma cells and Th2 in peripheral blood were lower than before treatment (P<0.05). After treatment, CD3+ T cells, CD4+ T cells, CD4+/ CD8+, ALB, PA, HGB, TRF, Th1 and Th1/Th2 in group C were higher than those in groups B and A (P<0.05), and the number of peripheral blood circulating hematoma cells and Th2 in group C were lower than those in groups B and A (P<0.05). Conclusion Shenqi Fuzheng injection combined with nutritional support can improve nutritional status and cellular immune function, maintain Th1/Th2 balance, reduce the number of circulating tumor cells in peripheral blood, improve treatment tolerance and reduce the incidence of adverse reactions in patients with locally advanced nasopharyngeal carcinoma