Abstract: Honokiol (HNK), one of major biological active constituents of Mangnolia officinalis, exerts a wide range of biological functions, such as moderate anticancer effects. It inhibits the growth of lung cancer, gastrointestinal cancer, head and neck squamous cell carcinoma, breast cancer, prostate cancer, ovarian cancer, in vitro and in vivo through multiple potential molecular targets. It modulates apoptosis-associated signaling pathway, inhibits growth factor receptor-mediated signal transduction pathway, blocks nuclear factor-κB signaling pathway, decreases the expression level of androgen receptors, subsides mTOR and STAT3 signaling pathway, and so on. HNK enhances the inhibitory effects of traditional anticancer drugs or targeted antitumor drugs in vitro and in vivo. It reverses multidrug resistances of cancer cells to cisplatin, doxorubicin and paclitaxol. Therefore, HNK plays a role in the augmentation of antitumor effects of cancer drugs and the reversal of multidrug resistance of tumor cells. HNK is a promising biochemical modulator of anti-cancer medicines in the cancer therapy.