BACKGROUND The aim of this study was to explore the effect and mechanism of tanshinone II A on proliferation, apoptosis, and migration of human colon cancer cells. MATERIAL AND METHODS CCK-8 approach was carried out to evaluate proliferation after applying various levels of tanshinone II A to SW620 colon carcinoma cells. Flow cytometry (FC) was used to assess apoptosis. Transwell assay was performed to assess invasion in vitro, and the wound-healing assay was applied to assess migration. Western blot analysis was performed to evaluate translation of mTOR, while RT-PCR was carried out to assess transcription of VEGF. RESULTS CCK-8 assay showed that tanshinone II A inhibited SW620 proliferation in comparison to the control group subsequent to 24 h, 48 h, and 72 h (P<0.001). FC revealed that tanshinone II A promoted SW620 apoptosis (P<0.001). The cell migration test revealed that the migration index of cells receiving tanshinone II A decreased. mTOR translation as well as VEGE transcription in cells receiving tanshinone II A was noticeably prohibited compared to control group (P<0.001). CONCLUSIONS Tanshinone II A is able to inhibit proliferation and migration of human colon cancer SW620 cells and promoted cell death. Its mechanism may be by downregulation of mTOR protein and VEGF mRNA.