The mechanism for Flos puerariae facilitating alcohol metabolism was studied.The relativity between particle size and the release rate of efficacy was demonstrated.The activity of alcohol dehydrogenase(ADH) in vitro and the dissolution of total material and flavonoids from four kinds of powder of Flos puerariae which used different methods to shatter were compared.The results showed that four kinds of powder could activate ADH,but grade Ⅱpowder had an obvious advantage over grade Ⅰpowder in the total dissolution test.Its instant dissolution can reached 8.6 times of that of plant body.There was the same trend in the amount of flavonoids dissolution and the activation rate of ADH.The amount of flavonoids dissolution in grade II powder was 57.98% higher than that in plant body and activation rate was 2 times of that in it.The grade Ⅱ powder which was gained by high efficient ball milling technology had a more beneficial effect on these tests than other powder.It was also indicated that it was useful to select Flos puerariae to facilitate alcohol metabolism,this new efficient technology provided a theoretical basis for the development of new sober up functional foods.