Objective: To explore the apoptosis mechanism of Wenxia Changfu Formula(温下肠腑方, WCF) in reversing drug resistance of lung cancer in vivo. Methods: Thirty model mice were randomly assigned to three groups: control group, cisplatin(CDDP) group, and WCF group. A transplanted tumor model of lung adenocarcinoma was established in all groups. Mice in the WCF group received intragastric administration of WCF(0.2 m L/10 g body weight) everyday in addition to CDDP intraperitoneally(5 mg/kg body weight) twice a week. The mice in the CDDP group received CDDP intraperitoneally(5 mg/kg body weight) twice a week, while the control group received normal saline intraperitoneally(0.2 m L/10 g body weight) everyday. The weight of the nude mice and respective tumors, tumor volume and tumor-inhibiting rate were measured. Electron microscopy was used to observe the existence of apoptosis body. Apoptosis index(AI) was detected by Td T-mediated d UTP nick end labeling staining. The expression of Fas and Fas L m RNA was investigated by reverse transcription polymerase chain reaction, while immunohistochemistry was applied to detect the protein expression of Fas and Fas L, caspase-3 and caspase-activated DNase(CAD), respectively. Results: Compared with CDDP group and control group, WCF could significantly reduce the tumor volume from the 19 th day and alleviate the tumor weight(P<0.05), and the apoptosis body was found in tumor cells in the WCF group. WCF could also enhance the level of AI, up-regulate the expression of caspase apoptosis pathway related protein caspase-3 and CAD, as well as the expression of Fas, Fas L m RNA and protein(P<0.05). Conclusion: WCF could improve the sensitivity of tumor cells to CDDP and reverse the drug resistance by inducing the apoptosis. Objective: To explore the apoptosis mechanism of Wenxia Changfu Formula (in Wuxia Wenchang Changfu Formula) in reversing drug resistance of lung cancer in vivo. Methods: Thirty model mice were randomly assigned to three groups: control group, cisplatin (CDDP) group , and WCF group. A transplanted tumor model of lung adenocarcinoma was established in all groups. Mice in the WCF group received intragastric administration of WCF (0.2 m L / 10 g body weight) everyday in addition to CDDP intraperitoneally (5 mg / kg body The mice in the CDDP group received CDDP intraperitoneally (5 mg / kg body weight) twice a week, while the control group received normal saline intraperitoneally (0.2 m L / 10 g body weight) everyday. The weight of the nude mice and the tumors, tumor volume and tumor-inhibiting rate were measured. Apoptosis index (AI) was detected by Td T-mediated d UTP nick end labeling staining. The expression of Fas and Fas L m RNA was investigated by reverse transcription polymerase chain reaction, while immunohistochemistry was applied to detect the protein expression of Fas and Fas L, caspase-3 and caspase-activated DNase (CAD), respectively. Results: Compared with CDDP group and WCF could significantly reduce the tumor volume from the 19 th day and alleviate the tumor weight (P <0.05), and the apoptosis body was found in tumor cells in the WCF group. WCF could also enhance the level of AI, up -regulate the expression of caspase apoptosis pathway related protein caspase-3 and CAD, as well as the expression of Fas, Fas L mRNA and protein (P <0.05). Conclusion: WCF could improve the sensitivity of tumor cells to CDDP and reverse the drug resistance by inducing the apoptosis.