Objective:To investigate influence of ultrafine grinding on stability of Qili powders.Method:Common powder and micropowder of Qili powders were placed in the high humidity

high temperature and lighting conditions separately

the moisture content

angle of repose

content of dracorhodin and in vitro dissolution were measured regularly.Result:Under the high humidity cindition

the moisture content of these two kinds of powders increaced

while the flowability and the content of dracorhodin droped significantly

dissolution of dracorhodin had no significant change.Under the high temperature condition

the moisture content of the common powder and the micropowder droped

the flowability increased while dissolution behavior of dracorhodin became bad

the content of dracorhodin in the common powder droped while there was no significant change in the micropowder.Under the lighting condition

the moisture content of these two kinds of powders increaced

while the flowability remained and the content of dracorhodin droped significantly

dissolution behavior of dracorhodin in the common powder became bad

but it kept stable in the micropowder.Conclusion:Compared with the common powder

in vitro dissolution stability of dracorhodin in the micropowder was worse under the high temperature

but the micropowder was more stable under the lighting condition.Change of each assessment index had no significant difference between the common powder and the micropowder under the remaining conditions.