Objective To observe the effect of combination

boiling time and administration time on diaphoretic function of Mahuang （Herba Ephedrae）. Methods One hundred SD rats were randomized into the blank group （n=20）

Mahuang group （n=40） and Mahuang-Guizhi （Ramulus Cinnamomi） group （n=40）. The rats in the above groups were randomized into 10 subgroups according to the administration need

with 10 in each. The blank group was divided to 2 subgroups and both administration groups were divided to 4 subgroups respectively. The experiment was conducted at room temperature of （25±1）℃ and the administration temperature was （35±2）℃. The dose in each group was 3 g/200 g. The blank group was given equivalent normal saline at temperature of （35±2）℃. The rats in other groups were given Mahuang or Mahuang-Guizhi decocted for 15 min or 30 min respectively. The colored points of sweat glands and sweat secretion of toe pad on the back foot were observed after 30min or 60 min of administration. Results The colored points of sweat glands and sweat secretion in the Mahuang-Guizhi group were significantly increased as compared with the blank group and Mahuang group at the same administration temperature and room temperature （P<0.05）. At the same administration time

the colored points of sweat glands and sweat secretion were significantly increased after 30min decoction as compared with after 15min decoction （P<0.05）. After same decoction time

the colored points of sweat glands and sweat secretion were significantly increased at 30 min after administration as compared with at 60 min after administration （P<0.05）. Conclusion The diaphoretic function of Mahuang-Guizhi decoction is most potent after 30 min decoction and at 30 min after administration.