Objective To investigate the inhibitory effect of Scutellaria baicalensis combined with 5-Fu on Lewis tumor bearing mouse lung cancer based on the JAK2 / STAT3 signaling pathway. Methods To detect the changes in body mass, food intake and tumor volume of Lewis tumor-bearing mice after intervention of Scutellaria baicalensis (20 mg / kg) combined with 5-Fu. Pathological changes in tumor tissue were observed by HE staining, expression levels of proliferation related protein Ki67 were observed by immunohistochemical staining, changes in cell apoptosis levels in tumor tissue were observed by TUNEL staining, and changes in expression levels of JAK2,p-JAK2, STAT3, and p-STAT3 proteins in tumor tissue were observed by immunohistochemical staining. Results Compared with the model group, the tumor volume of mice after combined intervention significantly decreased (P<0. 01) and body mass increased (i>P<0. 05), but there was no significant change food intake. The expression of proliferation related protein Ki67 in tumor tissue was significantly reduced, and the number of apoptotic cells labeled with TUNEL was significantly increased; The expression of p-JAK2 and p-STAT3 proteins is elevated. Conclusions Scutellaria baicalensis decoction can inhibit the JAK2 / STAT3 signaling pathway and increase the inhibitory effect of 5-Fu on mouse lung cancer.