Abstract: A microbial fermentation composition is prepared through after extracting and enzymolyzing selected Edible and medicinal fungi Agaricus blazei, Lentinus edodes, Flammulina velutipes and ginseng of reinforcing vital energy, adding trace elements selenium, zinc and molybdenum, and fermenting and transforming by probiotics. It is demonstrated through experiments of in vitro inhibition of HepGII cells (a liver cancer cell) and Hela cells (a cervical cancer cell) that the fermentation composition formed by probiotic fermentation has significant inhibitory effect on the proliferation of tumor cells. Compared with the non-fermented composition, the fermentation composition has a significantly enhanced inhibitory effect on experimental tumor cells and the difference is significant. The inhibitory effect of the fermentation composition on experimental tumor cells increases with the increase of the concentration.