Objective:To observe the effects of Yiqi Yangyin Jiedu Formula on advanced non-small cell lung cancer related immune indexes and serum sB7-H3,and explore the related mechanism based on the influence of costimulatory molecules on T lymphocyte immune response. Methods 60 patients with advanced non-small cell lung cancer who identified as the pattern of qi-yin deficiency in traditional Chinese medicine(TCM) syndrome differentiation were randomly divided into the treatment group and control group,30 cases in each group. The control group was only treated with chemotherapy,the treatment group was treated with Yiqi Yangyin Jiedu Formula additionally based on the treatment for the control group. All the treatments were given with a course of two cycles and one cycle was 21 days. The scores of TCM syndrome and eastern cooperative oncology group performance status(ECOGPS)were observed,and the levels of immune indexes(CD3,+,CD4,+,CD8,+,IL-2)and serum soluble costimulatory molecules sB7-H3 were detected and compared.  Results: ①For the comparison between the treatment before and after,the differences on the each and total score of TCM syndrome in the treatment group were all statistically significant(P,<,0.05),the differences on the single score of cough,expectoration,chest tightness,dry mouth and the total score of syndrome in the control group were statistically significant(P,<,0.05). For the comparison after treatment,there were statistically significant differences on the single score of chest pain,fatigue,anorexia,insomnia and the total score of syndrome between the two groups(P,<,0.05). ②For the comparison between the treatment before and after,the difference on the ECOGPS score in the treatment group was statistically significant(P,<,0.05),but the difference on the ECOGPS score in the control group was not statistically significant(P,>,0.05). For the comparison after treatment,there was statistically significant difference on the ECOGPS score between the two groups(P,<,0.05). ③For the comparison between the treatment before and after,the differences on the levels of IL-2 and sB7-H3 in the treatment group were statistically significant(P,<,0.05),but the differences on the levels of all indexes in the control group were not statistically significant(P,>,0.05). For the comparison after treatment,there were statistically significant differences on the levels of CD4,+,IL-2,sB7-H3 between the two groups(P,<,0.05).  Conclusion: Yiqi Yangyin Jiedu Formula can improve the syndrome of qi-yin deficiency in patients with lung cancer,increase the proportion of CD4,+, cells and the level of IL-2,reduce the serum level of sB7-H3.