A production method effectively increases the amount and yield of mushroom beta-glucan, and widely applied in the fields of food, biotechnology, cultivation and medical development. The cultivating medium contains the nutrition of three natural grains, including brown rice, adlay and oat, to provide a complete physiological environment for the mushrooms to grow well. Experimental results strongly suggest that AMFM treated cell activities are significantly enhanced in comparison with those without AMFM treated.