Tumor recurrence and drug resistance are the main obstacles blocking effective treatment of cancer patients. Cancer stem cells (CSCs) have been demonstrated to be highly related to tumor recurrence and drug resistance. Thus, eliminating CSCs may be an alternative for cancer therapy. Tumor sphere formation is a functional assay to enrich the CSC-like cells. In the present study, we tested the effects of curcumin on lung cancer stem-like cells and report that in addition to inhibition on the proliferation and colony formation of lung cancer cells, curcumin reduces tumor spheres of H460 cells. Moreover, by molecular docking analysis and tumor sphere assay we discover that curcumin was able to inhibit JAK2 activity and reduce tumor spheres via inhibiting the JAK2/STAT3 signaling pathway. In a lung cancer xenograft nude mouse model, curcumin strongly repressed tumor growth. These results imply curcumin may be a potential drug in lung CSC elimination and cancer therapy.