||Objective: To investigate the action mechanism of acupuncture for non.insulin resistant polycystic ovary syndrome (PCOS). Methods: A total of 46 cases with non`insulin resistant PCOS were randomly allocated into an observation group of 23 cases and a control group of 23 cases. Cases in the observation group were treated by needling bilateral Weiwanxiashu (Ex-B 3), whereas those in the control group were treated by needling bilateral Sanyinjiao (SP 6). After 3-month treatments, a comparison was made on the changes of ovulations rates, Follicle-stimulating hormone (FSH), luteinizing hormone (LH), testosterone(T), fasting insulin and body mass index (BMI). Results: There were statistical differences in ovulation rates and LH/FSH before and after the treatment in the observation group (P<0.05), along with a statistical difference in testosterone changes (P<0.01). There were also statistical differences in LH and LH/FSH before and after the treatment in the control group (P<0.05); however, there were no statistical differences in ovulation rates and testosterone changes (P>0.05). There was significant difference in testosterone changes between the two groups after the treatment (P<0.01), along with a statistical difference in ovulation rates between the two groups (P<0.05). However, there were no statistical differences in LH/FSH and BMI between the two groups. Conclusion: Needling Weiwanxiashu (Ex-B 3)and Sanyinjiao (SP 6 can both improve the endocrine disorder of patients with non-insulin resistant PCOS; however, needling Weiwanxiashu (Ex-B 3) can obtain a better result than Sanyinjiao (SP 6) in increasing the insulin sensitivity and preventing insulin resistance.