In this study, 70 new seco-lupane triterpene derivatives were designed, synthesized, and characterized, and their in vitro anticancer activities were evaluated. Structure–activity relationship studies showed that most compounds inhibited the growth of a variety of tumor cells in vitro. With the extension of alkyl chains, the activity of azole compounds gradually increased while that of indole compounds first increased and then decreased. Moreover, all indole derivatives showed stronger anticancer activity than azole derivatives. In addition, compound 21 showed the strongest inhibitory effect on HepG2 cells with an IC50 value of 0.97 μM. Mechanistic studies showed that compound 21 coregulates the cell death process by inducing ferroptosis and regulating the cell cycle. In conclusion, compound 21 can be used as a ferroptosis inducer and cycle blocker to regulate the HepG2 death process, and it has the potential to become an effective new drug for the treatment of hepatocellular carcinoma.