Objective: To observe the influence of Fuzheng Quxie decoction on the basis of paclitaxel + cisplatin (TP) chemotherapy regimen on immune function and toxic and side effects in patients with lung cancer. Methods: A total of 114 patients with lung cancer admitted to department of medical oncology of Wugang People’s Hospital from January 2023 to September 2024 were selected and divided into conventional group and traditional Chinese medicine group according to the random number table method, with 57 cases in each group. The conventional group received TP chemotherapy, while the traditional Chinese medicine group was added with modified Fuzheng Quxie decoction on the basis of the conventional group. The efficacy of TCM symptoms, and levels of tumor markers and immune function indexes before and after treatment were observed in the two groups. The toxic and side effects of patients during treatment were counted. Results: The total effective rate of treatment in traditional Chinese medicine group was significantly higher than that in conventional group (P<0.05). After 5 courses of treatment, the levels of carcinoembryonic antigen (CEA), carbohydrate antigen 125 (CA125) and neuron-specific enolase (NSE) in the two groups were significantly decreased (P<0.05), and the levels of CEA and CA125 were lower in traditional Chinese medicine group than those in conventional group (P<0.05). After 5 courses of treatment, the cluster of differentiation 4 positive (CD4+) T cell subset and CD4+/CD8+ ratio in traditional Chinese medicine group were significantly enhanced compared with those before treatment (P<0.05), and the indexes were higher in traditional Chinese medicine group than those in conventional group (P<0.05). The CD8+ T cell subset in both groups after 5 courses of treatment was lower than that before treatment (P<0.05), but the level in traditional Chinese medicine group was higher than that in conventional group (P<0.05). Within 5 courses of treatment, there were no deaths (grade 5) in both groups. The severities of nausea and vomiting, anemia and leukopenia in traditional Chinese medicine group were milder than those in conventional group (P<0.05). Conclusion: Fuzheng Quxie decoction on the basis of TP chemotherapy regimen can synergistically enhance the therapeutic efficacy on lung cancer, effectively reduce the expressions of tumor markers, and improve the body’ s immune function, with good safety.