To explore the clinical efficacy of Danggui Shaoyao Powder in the treatment of primary dysmenorrhea(PD).Methods:A total of 72 PD patients with qi stagnation and blood stasis，meeting the inclusion criteria，were randomly divided into observation group and control group，with 36 patients in each group.The observation group was treated with Danggui Shaoyao Powder and the control group was treated with Yuanhu Zhitong Tablets.The patients in both groups started medication one week before menstruation，with each course lasting for 10 days and a total of 3 courses.The changes in traditional Chinese medicine(TCM) syndrome scores，serum prostaglandinF2α(PGF2α) and cyclooxygenase 2(COX-2) were observed before and after treatment in both groups.Results:After treatment，the total effective rate in the observation group and control group was 97.14% and 63.64%，respectively，with statistical significance(P<0.05).The TCM syndrome scores of the observation group after treatment were lower than those of the control group，and the differences were statistically significant(P<0.05).The levels of serum PGF2α and COX-2 in the observation group were lower than those in the control group，and the differences were statistically significant(P<0.05).Conclusion:Danggui Shaoyao Powder can relieve the symptoms of PD by inhibiting the expression of COX-2 and reducing the level of PGF2α without causing adverse reactions in clinic.