Background:: The anti-cancer activity of andrographolide (Andro) has been extensively demonstrated in recent years. It is supposed that modifying the chemical structure of Andro can improve its efficacy and reduce its toxicity. Purpose:: In this study, the anti-cancer effect of a 14β-(2′-chlorophenoxy) derivative of andrographolide known as AGS-30 was investigated, and its underlying mechanisms were also explored. Study Design/Methods:: Different cancer cells were used to evaluate and compare the in vitro anti-cancer effects of Andro and AGS-30. Human colon cancer cells HT-29 and HCT-116 were used to study the underlying anti-cancer mechanisms of AGS-30. HT-29 cells xenografted in nude mouse model was used to compare the in vivo anti-tumour efficacies of Andro and AGS-30. Result:: In vitro studies showed that AGS-30 possessed an anti-cancer effect by inhibiting the viability, colony formation and migration of cancer cells. It significantly induced the generation of reactive oxygen species (ROS), caused the loss of mitochondrial membrane potential and triggered the apoptosis in colon cancer cells. These effects of AGS-30 were more potent than those of Andro. In addition, the expression levels of proteins associated with apoptosis, including phospho-JNK1/2 as well as cleaved caspase 9, caspase 3, and poly(ADP ribose) polymerase, were elevated in AGS-30-treated colon cancer cells. Moreover, these elevated levels of the proteins were inhibited by the antioxidant N-acetylcysteine and the JNK inhibitor SP600125, suggesting the involvement of ROS/JNK-dependent mechanisms in AGS-30-induced apoptosis. The in vitro anti-cancer effect could be reproduced in an HT-29 colon cancer cell xenografted nude mouse model. Conclusion:: The anti-cancer effect of AGS-30 is stronger than that of Andro. AGS-30 induces apoptosis of colon cancer cells through ROS/JNK-dependent pathway. Our findings may provide insights for the future development of derivatives of Andro as novel chemotherapeutic agents.