Abstract: Objective To investigate the relation between the function state of mTOR signal pathway and rapamycin sensitivity to lung cancer. Methods mTOR signaling pathway protein in ４ lung cancer cell lines (HLAMP,H1299,A549 and PAa) were detected by Western Blot．MTT method was used to determine the inhibitory effect of rapamycin on human lung cancer cell．Lung cancer cell lines were divided into rapamycin sensitive group and non-sensitive group.En Vision method was used to detecte the expression of rapamycin differential protein in 100 lung cancer and 20 lung nonmalignant disease normal lung tissues.ResultAKT,S6K1,4E-BP1,eIF4E were expressed in all human lung cancer cell lines.P-S6K1 was high-level expression in sensitive cell lines, no detection in non-sensitive cell line,and it was arapamycin differential protein.P-S6K1 positive-expression rate was 15%（3/2０）in normal lung tissues, and 62%(62/100) in lung cancer,respectively.P-S6K1 positive-expression rate in small cell lung cancer (81%,17/21)was higher than that in non-small cell lung cancer (59%,45/79). Conclusion The expression of P-S6K1 in human lung cancer cell lines may reflect rapamycin sensitivity to cancer cell to a extent.But other mTOR signaling pathway protein（AKT,S6K1,eIF4E, 4E -BP1）can not reflect rapamycin sensitivity to lung cancer cell．P-S6K1 isarapamycin differential protein．The expression of P-S6K1 in small cell lung cancer is much higher than that in non-samll cell lung cancer.The results suggest the better clinical effect of mTOR inhibitor-rapamycin in small cell lung cancer.