The invention relates to a method for extracting bioactive beta-glucan from liquid fermented sparassis crispa mycelia. By the method, high-efficiency, low-cost, high-yield and high-quality production of the beta-glucan can be effectively achieved. The method comprises the following steps: culturing the sparassis crispa mycelia by using a culture medium, collecting the sparassis crispa mycelia, washing off the culture medium with distilled water, homogenizing, then treating in a high-pressure cell disrupter to obtain liquid treated under high pressure, centrifuging, heating a supernatant, recentrifuging, adding absolute ethanol into the supernatant, precipitating, then centrifuging, discarding the supernatant, rinsing a precipitate for 2 times with ethanol, collecting the precipitate, and lyophilizing the precipitate to obtain the sparassis crispa beta-glucan. By the method, raw materials are rich, the production method is simple and easy to operate, the production efficiency is high, the yield is high, the product quality is high, the production of the beta-glucan is effectively achieved, and the actual needs in industrial production are met; the method can be effectively applied to medicines, health products and cosmetics and is wide in application; and by the method, significant economic and social benefits are achieved.