Emodin is one of the main active ingredient of Rheum palmatum, and has anti-inflammatory, anti-bacterial, anti-viral and other effects. In recent years, it arouse concern since it has a significant anti-tumor effect with low toxicity. In this paper we mainly report the anti-cancer effects of emodin according to the studies of the past five years, including four parts such as inhibit tumor growth, inhibit migration and invasion, enhance the efficacy of combination therapy, increase chemosensitivity and attenuated side effects. We hope that our work may provide a reference for further study.