〔Abstract〕 Objective To investigate the effect of Rotundic acid(RA) on proliferation, migration and invasion ability of human lung adenocarcinoma cells as well as its possible mechanisms. Methods Human lung adenocarcinoma A549 and PC9 cells were divided into control group, blank control group, solvent group and 20, 40, 60, 80 μmol/L RA groups. CCK-8 assay and scratch assay were used to detect the proliferation and horizontal migration of human lung adenocarcinoma cells. Transwell migration assay and Transwell invasion assay were used to detect the longitudinal migration and invasion ability of A549 and PC9 cells in each group. The protein expression levels of janus kinase 2(JAK2) and signal transducer and activator of transcription 3(STAT3) in the supernatants of A549 and PC9 cells were detected by ELISA. The mRNA expression levels of JAK2 and STAT3 were detected by RT-PCR. Statistical analysis was made on the differences among groups in each index. Results After RA treatment on human lung adenocarcinoma cells, compared with the control group, the proliferation activity of A549 and PC9 cells in the experimental groups decreased(P<0.05), the number of cells crossing polycarbonate membrane and matrix glue decreased(P<0.05), the expression of JAK2 and STAT3 proteins in cell supernatant decreased(P<0.05), and the mRNA expression of JAK2 and STAT3 decreased(P<0.05). The decrease of the above indices was concentration-dependent and had statistical significance(P<0.05).Compared with the control group, the proliferation activity of A549 and PC9 cells in the solvent group showed no significant difference. Conclusion RA may inhibit the proliferation, migration and invasion of human lung adenocarcinoma A549 and PC9 cellsin vitro, possibly through the inhibition of JAK2/STAT3 pathway.