The effect of different Co 60 γ irradiation dosages of 0.4,1.2, 1.6 and 2.0?kGy on the fresh keeping of Agaricus Bioporus was studied. The results showed that mushroom radiated with γ had lower rates of membrane split, opening of pilei, browning and decomposition as well as the lose of fresh weignt. The fresh keeping period of mushroom radiated with 1.2kGy dosage and stored at low temperature (4?℃) was prolonged to 30 days.