Abstract: The hot air drying characteristics of mushroom stem were studied in this paper,and the physicochemical properties of its coarse powder and micro- powder were comparatively analyzed. Results showed that the drying time of mushroom stem was shortened with the increase of hot air temperature and the decrease of slice thickness,and the coarse powder under hot air temperature 50 ℃ had greater nutrient retention and better color.Compared to the coarse powder,the micro- powder had a little worse color,but had a better fluidity,higher values in the bulk density,water holding capacity,water soluble index,swelling capacity,oil holding capacity,and lower values in the angle of repose and slip angle. Meanwhile the micro- powder possessed higher values in dietary fiber,soluble protein and polysaccharide content. Therefore,after superfine grinding,the powder had a promotion on physical properties and nutrient content.