To study the effects of Yiqi Huatan Decoction adjuvant therapy on chemosensitivity in advanced non-small cell lung cancer(NSCLC)patients and its mechanism.Methods:A total of 80 cases of advanced NSCLC patients in Benxi City Center Hospital during August 2012 to September 2017 were divided into a control group(n=40)underwent conventional chemotherapy and an observation group(n=40)underwent Yiqi Huatan Decoction adjuvant therapy combined with conventional chemotherapy according to the random number table.The difference of tumor absolute volume，contents of tumor markers and neovascularization markers，and the expression of resistance genes in the biopsy tissues of the 2 groups were compared before and after treatment.Results:Before treatment，there were no significant difference between the 2 groups in total volume of tumor，contents of tumor markers and neovascularization markers，expression of resistance genes in the biopsy tissue between the 2 groups(P>005)2 courses after treatment，the absolute volume of primary lung tumor in the observation group was less than that in control group; serum contents of tumor markers such as SCC-Ag，CYFRA21-1 and CA125 were lower than those in the control group; serum contents of neovascularization markers such as MMP-2，VEGF and ET-1 in the observation group were lower than those in the control group，and TSP-1 was higher than that in the control group; the expression of resistance genes such as MRP，MDR1，LRP mRNA in the observation group were lower than those in the control group(P<005).Conclusion:Yiqi Huatan Decoction adjuvant therapy for advanced NSCLC patients bases on chemotherapy，can further enhance the sensitivity of chemotherapy，which is directly related to the drug resistance gene expression.