Paeonol is the main active component of Moutan Cortex and Cynanchum paniculatum. In recent years, paeonol has been paid more attention to because of varieties of pharmacological activities, antibacterial and anti-inflammatory activities, improving the immune system, etc. Meanwhile, the antitumor effect of paeonol has become a research focus recently. For instance, paeonol can inhibit the development of liver cancer, colon cancer, and stomach cancer by inhibiting the proliferation of cancer cells, inducing apoptosis and improving immunity. In this paper, experimental studies related to the antitumor effect of paeonol were reviewed. Antitumor mechanisms of paeonol were discussed to provide references for further study of the pharmacological effects of paeonol.