To explore the clinical efficacy of S-1 capsule combined with modified Liujunzi Decoction in the third-line treatment of advanced lung squamous cell carcinoma in elderly patients with lung-spleen qi deficiency syndrome.Methods:A total of 100 elderly patients with advanced lung squamous cell carcinoma admitted to the department of oncology,Zhongshan Hospital of traditional Chinese medicine from January 2017 to November 2018 were randomly divided into an observation group and a control group,with 50 cases in each group.All patients had undergone first-line and second-line chemotherapy progress,and syndrome differentiation was lung-spleen qi deficiency syndrome.The experimental group was treated with S-1 capsule combined with modified Liujunzi decoction,while the control group was treated with modified Liujunzi Decoction.The therapeutic effects of the 2 groups were compared.Result：The total effective rate of physical condition in the observation group was 88%,and the control group was 48%.The difference between the 2 groups was statistically significant (P<0.05).There was no significant difference in tumor size between the 2 groups before treatment (P>0.05).The results of CT examination at 2,3,6 and 12 months after treatment showed that the tumor volume in the observation group gradually became smaller,reaching (11.89±2.67) cm2 after 12 months,while the tumor size in the control group did not change much.The difference between the 2 groups was statistically significant (P<0.05).There was no significant difference in the incidence of common adverse reactions (myelosuppression,nausea and vomiting,alopecia) between the 2 groups (P>0.05).Conclusion:Compared with modified Liujunzi Decoction alone,the treatment of S-1 capsule combined with modified Liujunzi Decoction is better in the treating elderly patients with advanced lung squamous cell carcinoma.The adverse reactions are not increased,which can be promoted to the third-line treatment of advanced lung squamous cell carcinoma with lung-spleen qi deficiency syndrome in the elderly.