Yun Zhi Polysaccharides (PSP) is a new type of BRM (Biological Response Modifier) extracted from the deep layer cultivated mycelia of Cov-1 strain of Yun Zhi (Coriolus versicolor). Its active ingredient is a protein bound polysaccharides used in the BRM therapy of tumors. Its characteristics and the general aspects of its research are briefly introduced in this paper