Poria cocos polysaccharide is a medicinal substance derived from dried sclerotium, mycelium and fermentation broth of Poria cocos. It exhibits various biological activities, including anti-tumor, anti-inflammatory, antioxidant and antidepressive effects. Poria cocos polysaccharide is mainly used in clinical practice to treat malignant tumors, colitis and depression and other diseases. With the in-depth study of the anti-tumor mechanism of Poria cocos polysaccharides, researchers have found that it exerts anti-tumor effects through immune regulation, inhibition of tumor cell proliferation, anti-angiogenesis and genetic regulation, and is widely used in the treatment of liver cancer, lung cancer and breast cancer. This article will comprehensively and systematically summarize the latest mechanism of action of Poria cocos polysaccharides against tumors, providing basic data and theoretical basis for the clinical application of the antitumor effect of Poria cocos polysaccharides and the development of new drugs.