Objective To evaluate the clinical efficacy of Targeted Ⅱ Formula(composed of Astragali Radix,Pseudostellariae Radix,Ophiopogonis Radix,Asparagi Radix,Glehniae Radix,Rehmanniae Radix,Ligustri Lucidi Fructus,Ecliptae Herba,Polygonati Rhizoma,Polygonati Odorati Rhizoma,etc.)in delaying epidermal growth factor receptor(EGFR)tyrosine kinase inhibitors(TKIs)resistance in EGFR mutation-positive non-small cell lung cancer(NSCLC)patients with.Methods Between January 1,2019 and June 30,2023,64 NSCLC patients with qi-yin deficiency syndrome treated at Shanghai Pulmonary Hospital(affiliated to Tongji University)were stratified based on their 1-month post-targeted therapy response and then were randomized into a treatment group(receiving Icotinib plus Targeted Ⅱ Formula decoction)or a control group(receiving Icotinib alone).Patients were followed-up until disease progression.Progression-free survival(PFS),adverse events,quality of life,and immune function were assessed.Results(1)In terms of PFS,the mean PFS in the treatment group was(18.78±7.17)months,while that in the control group was(11.76±4.26)months.The PFS in the treatment group was significantly longer than that in the control group,with a statistically significant difference(P＜0.001);the 1-year PFS rate in the treatment group was 87.50％(28/32),significantly higher than the 38.71％(12/31)in the control group,with a statistically significant difference(P＜0.001).(2)In terms of adverse reactions,the incidence of targeted drug-related rash in the treatment group was 68.75％(22/32),lower than that of the control group(80.65％,25/31),but the difference between the two groups was not statistically significant(P＞0.05).In terms of rash grading,both groups primarily had Grade 1 rashes,and the treatment group had fewer Grade 2 and 3 rashes than the control group,indicating that the severity of rashes was more pronounced in the control group.(3)In terms of quality of life,after treatment,the Karnofsky Performance Status(KPS)score in the treatment group significantly increased compared to before treatment(P＜0.05),while the control group showed no significant increase compared to before treatment(P＞0.05).The intergroup comparison revealed that the increase of KPS scores in the treatment group was significantly greater than that in the control group,with a statistically significant difference(P＜0.05).(4)In terms of immune function,after treatment,the levels of CD8+T lymphocytes and interferon-γ(IFN-γ)in peripheral blood were significantly higher in the treatment group than before treatment(P＜0.05),while those in the control group were significantly lower than before treatment(P＜0.05);Intergroup comparisons revealed that the treatment group exhibited a significantly greater reduction in peripheral blood CD8+T lymphocyte and IFN-γ expression levels compared to the control group,with statistically significant differences(P＜0.05).Conclusion This study employed an innovative stratified randomization design to eliminate bias in Icotinib efficacy.The results demonstrate that Targeted Ⅱ Formula effectively delays EGFR-TKI resistance,mitigates adverse events,and improves quality of life in EGFR mutation-positive NSCLC patients with qi-yin deficiency syndrome,supporting its role as an adjuvant therapy in targeted lung cancer treatment.