Abstract：Objective：To observe the clinical effect of sequential therapy of high-dose modified Sijunzi Decoction for non- small cell lung cancer (NSCLC) in the middle and late stage in the senile. Methods：A total of 90 cases of senile patients with NSCLC in the middle and late stage were selected and divided into the control group and the experiment group according to the random number table method，with 45 cases in each group. The control group was given symptomatic support treatment，and the experiment group was given sequential therapy of high- dose modified Sijunzi Decoction based on the treatment of the control group. Both groups were treated for 35 days. Before and after treatment，the traditional Chinese medicine (TCM) syndrome scores， Karnofsky Performance Status (KPS) scores， Chinese version of Functional Assessment of Cancer Therapy- Lung (FACT- L) V4.0 scores， and immune function index levels were compared between the two groups. The incidence of adverse reactions was recorded. Results： After treatment， the TCM syndrome score in the experiment group was decreased when compared with that before treatment，and lower than that in the control group (P＜0.05)；there was no significant difference in the TCM syndrome score before and after treatment in the control group (P＞0.05). The KPS score in the experiment group was increased when compared with that before treatment，and was higher than that in the control group (P＜0.05)，and the KPS score in the control group was decreased when compared with that before treatment (P＜0.05). The scores of physical and functional status in the experiment group were better than those in the control group (P＜0.05)， and the scores of social and family status， emotional status，and additional attention between the two groups showed no significant differences (P＞0.05). The levels of CD3 + and CD4 + in the experiment group were increased when compared with those before treatment (P＜0.05)，and the level of natural killer cell (NK cell) was decreased when compared with that before treatment (P＜0.05)； the levels of CD3 + and CD4 + in the control group were decreased when compared with those before treatment (P＜0.05)，and the level of NK cell showed no significant difference before and after treatment (P＞0.05). There was no significant difference being found in the comparison of gastrointestinal reactions，bone marrow suppression，liver function damage and kidney function damage classification between the two groups (P＞0.05). Conclusion： Sequential therapy of high- dose modified Sijunzi Decoction for senile NSCLC in the middle and late stage can alleviate the clinical symptoms of patients，improve their quality of life，enhance immune function，and have good safety.