Objective To compare the pharmacologic effect of Guizhi Decoction with dosage of different convert criterion.Methods The 40 Wistar rats were randomized into blank group

model group

Guizhi Decoction large and small dosage groups

with 10 in each. The effect of Guizhi Decoction on the body temperature of rats with fever induced by yeast at different time points and the changes in concentration of interleukin-1 （IL-1） and tumor necrosis factor-α （TNF-α） in serum and prostaglandin E2 （PGE2） in plasma and hypothalamus were observed.Results The body temperature of rats with yeast injection through nape at the time point of 4.5h was significantly increased （P<0.05）; the body temperature of rats in the model group at the time point of 6.5h was increased more significantly than that in Guizhi Decoction large dosage group （P<0.05）; compared with the model group

the body temperature of rats in Guizhi Decoction large and small dosage groups decreased at the time point of 7.5h （P<0.05）; the body temperature of rats in Guizhi Decoction large dosage group was nearly normal at the time point of 8.5h. The concentration of IL-1 and TNF-α and PGE2 of rats in model group was significantly higher. The decrease of IL-1 and TNF-α and PGE2 of rats in Guizhi Decoction large dosage group was more significant than that in Guizhi Decoction small dosage group.Conclusion Guizhi Decoction at the convert criterion of 1Liang =13.8g has a significant effect of clearing heat. Its mechanism may be related to its function in decreasing IL-1 and TNF-α and PGE2.