Abstract: The effects of different doses of UV- C irradiation( 0,0.3,0.6,0.9,1.2 k J / m2) on physicochemical responses and microbial characteristics on the storage of Agaricus bisporus under low temperature( 4 ℃) were studied.Mushroom weight loss,firmness,color,total soluble solids,activities of polyphenol oxidase( PPO) and microbial were measured.The results showed that UV- C treatment in 0.6 k J / m2 could disinfect microorganism in a certain extent,minish membrane permeability,inhibit PPO activity and delay browning,but no significant difference.The more obvious effects of reduction in microbial counts compared with the control could be found with elongation of UV- C irradiation.The high doses of UV- C treatment could delay the changes in firmness and total soluble solids.But at the same time,damages such as browning and membrane permeability enhancement would be stronger.