To explore the mechanism of Fuzheng Jiedu Formula in improving the mechanism of gefitinib-acquired resistance.Methods:Lung cancer stem cell tumor-bearing mouse model was established and were randomly divided into a saline group，a gefitinib group and a Fuzheng Jiedu Formula combined with gefitinib group，a Chinese medicinal of detoxication combined with gefitinib group.The tumor inhibition rate of tumor-bearing mice was measured，ARMS method was used to detect tumor tissue T790M mutation，RT-PCR method was used to detect tumor tissue c-Met gene amplification.Results:Gefitinib，the single drug，the tumor inhibition rate of gefitinib single agent on lung cancer stem cell tumor-bearing mice was 31.02%; the Chinese medicinal for strengthening vital qi and detoxication combined with gefitinib was 33.43%; the Chinese medicinal of strengthening vital qi and detoxication combined with gefitinib group was 37.51%; the Fuzheng Jiedu Formula combined with gefitin was 45.11%.The difference between the above groups and the normal saline group was statistically significant(P<0.05 or 0.01); the difference between the Fuzheng Jiedu Formula combined with gefitinib group and the gefitinib single-drug group was statistically significant(P<0.05).Further studies have shown that the T790M gene mutation and c-Met gene amplification in the gefitinib single-agent group were significantly increased，and the difference was statistically significant compared with the normal saline group(P<0.01).Fuzheng Jiedu Formula combined with gefitinib can reduce T790M gene mutation and c-Met gene amplification，compared with the gefitinib single-drug group，the difference was statistically significant(P<0.05).Conclusion:Fuzheng Jiedu Formula can improve acquired resistance of Gefitinib，and the mechanism is related to decrease of EGFR T790M gene mutations and c-Met gene amplification of tumors.