Objective: To investigate the influence of Siwu decoction and its composite drug-pairs or drugs on the primary dysmenorrheal model of mouse so as to clarify the potential mechanism and compatible regularity of Siwu decoction. Method: The model of primary dysmenorrheal mice were used to investigate the effect of Siwu decoction on the writhing response and the levels of nitric oxide and calcium ion in mice uterine tissue. Result: Siwu decoction and its composite drug-pairs and drugs had certain pharmacological effect on primary dysmenorrheal by reducing the writhing times

increasing nitric oxide (NO) levels and reducing calcium ion (Ca2+) concentration in uterine tissue of mice. Conclusion: Siwu decoction and its composite drug-pairs and drugs exhibited characteristic influence on the primary dysmenorrheal model of mouse. The drug of Rehmanniae Radix Praeparata might have the antagonistic effect to Chuanxiong Rhizoma

Angelicar Sinensis Radix and Paeoniae Radix Alba on the activity of reducing the model mice’s writhing times. The drug-pair of Angelicar Sinensis Radix and Paeoniae Radix Alba may be the most significant drug-pair for the treatment effect on the model of primary dysmenorrheal mice. This study provided a reliable reference for the follow-up study.