Abstract: The spray drying powder of blanching water for Stropharia rugoso-annulata falow was studied to understand its changes in physical characteristics,hygroscopicity,free radical scavenging activity during storage period. The results showed that, the lower of storage temperature for spray drying powder, the higher in scavenging efficiency of it for ·OH free radical, and the longer in its half-lost time. The low temperature preservation was suggested for spray drying powder and it should be under the 20℃. With same storage temperature, its half-lost time in darkness was longer than it exposed in light and the higher the relative humidity, the faster the moisture absorption was. According to the difference of moisture content between spray drying powder and packing standard, the release time before packing of the spary drying powder was suggested 0.34 hour even under 92.31% of relative moisture. The results indicated that stropharia rugoso-annulata blanching powder by spray drying revealed a good stability while stored under low temperature、low humidity and dark conditions, especially in avoiding moisture regain during the storage period.