[Objective] The research aimed to discuss the biochemical mechanism of Agaricus blazei Murill.in the process of enriching selenium.[Method] Sodium selenite solution with the concentration of 0,30,60,90,120,150 mg/L were added to the medium of A.blazei mycelia to study the effects of different concn.of selenium on the activities of peroxidase(POD) and superoxide dismutase(SOD),malondialdehyde(MDA) content in the mycelium of A.blazei.[Result] When the concn.of selenium was 150 mg/L,POD activity in the myceliu...