Objective:To investigate the influence of Gegen decoction（GGD） and the potential mechanism on primary dysmenorrhea with cold-damp coagulation induced byoxytocin and cold simulating.Method:Seventy female ICR mice were randomly divided into seven groups:normal group

model group

buprofen group

Guizhi Fuling capsule group

low-dose GGD group

middle-dose GGD group and high-dose GGD group.Subcutaneous injection of estrogen and cold stimulation were used for 3 consecutive days

and peritoneal injection of oxytocin on the 4th day to construct primary dysmenorrhea model with cold-damp coagulation

the writhing response and the levels of nitric oxide（NO） and calcium ion（Ca2+） in mice uterine tissue were investigated.Meanwhile

ibuprofen group received ibuprofen（0.12 g · kg-1）

GFC group received Guizhi Fuling Capsule（1.12 g · kg-1）

GGD group received GGD（low-dose

3.5 g · kg-1;middle-dose

7.0 g · kg-1;high-dose

14.0 g · kg-1）.Result:GGD could inhibit the writhing response effectively（the inhibition rate was 81.03%

84.14%

90.15% at low

middle and high-dose

respectively） and increase NO levels and reduce Ca2+ concentration in uterine tissue of mice（P<0.001）.The efficacy of GGD was equal to the positive drug ibuprofen and Guizhi Fuling capsule.Conclusion:GGD could effectively alleviate the spasm of uterine smooth induced by oxytocin and cold.The mechanism might be relative to regulation of uterine NO and Ca2+ levels.