Objective To investigate the effects of dietary anti - inflammatory index on immune function inflammatory factors cancer-related fatigue and chemotherapy toxicity in lung cancer patients receiving chemotherapy. Method A total of 133 lung cancer patients who received chemotherapy in Tangdu Hospital of Air Force Military Medical University from February 2020 to December 2023 were selected as the study objects. According to different selection times 66 lung cancer patients who received conventional diet management from February 2020 to December 2021 were set as the control group. A total of 67 patients with lung cancer who received nutritional support based on dietary anti-inflammatory index from January 2022 to December 2023 were selected as the experimental group. The nutritional status immune function cancer fatigue and inflammatory factors before chemotherapy were compared and the toxic and side effects during chemotherapy were observed. Result At T1 T2 and T3 TP ALB PA CD4 + CD8 + CD4 + / CD8 + in observation group were higher than those in control group while hs-CRP and IL-6 were lower than those in control group P<0. 05 . At T3 time point the scores of physical fatigue emotional fatigue and cognitive fatigue in the Cancer Fatigue Scale CFS of the experimental group were lower than those of the control group P<0. 05 . The incidence of leukopenia thrombocytopenia nausea vomiting and diarrhea in observation group were lower than those in control group P<0. 05 . Conclusion Nutritional support based on dietary anti-inflammatory index can improve the nutritional status immune function and reduce cancer fatigue in lung cancer patients treated with chemotherapy which has a positive effect on improving the chemotherapy effect.